Motor Vehicle Body and Trailer Manufacturing (U.S.) — NAICS 33621

A Histometrics industry-group primer. NAICS (North American Industry Classification System) 2022 code 33621 is a five-digit "industry" that bundles four related but economically distinct businesses. This primer synthesizes the four child primers and our ground-truth federal statistics for the combined level; forward-looking statements are framed as judgments, not facts.

1. Overview

NAICS 33621 gathers under one roof every plant that builds a vehicle body, trailer, or towable but not the complete self-powered vehicle underneath it. That single code spans two economies that rarely move together:

• Work / commercial vehicles — truck bodies (336211) and freight trailers (336212). These serve businesses and governments: delivery vans, dump and service bodies, fire trucks and ambulances, and the semi-trailers that haul most U.S. freight. Trucks moved roughly 8.3 billion tons of goods (68.1% of reported tonnage) worth $13.2 trillion (73.5% of reported value) in the 2022 Commodity Flow Survey.[25] Their cycle is the freight-and-construction cycle.
• Recreational vehicles (RVs) — motorhomes (336213) and towable travel trailers and campers (336214). These serve consumers buying a big-ticket discretionary toy. Their cycle is the interest-rate-and-consumer-confidence cycle.

Why an investor should care: this is one NAICS industry, but it is really two bets — and, on the 2026 evidence, arguably more than two. The commercial half tracks trucking, e-commerce delivery, and municipal budgets; the recreational half tracks household credit and confidence. They can be up and down at the same time, and in the first half of 2026 the two recreational children themselves split apart: motorhome shipments ran +11.8% year over year through May while total RV shipments fell 14.4% and towables fell 17.2%.[6] Understanding 33621 means understanding which half — and increasingly which child — you are actually buying, because the concentration, ownership, and "how to invest" answers differ sharply across the four, which is where this primer starts (Section 2).

A structural feature runs through all four: none of these plants builds the drivetrain. Each buys a chassis (frame plus running gear) or a component set from an automaker and adds the body, box, or living quarters on top. That keeps the priciest part off the builder's balance sheet, ties output to chassis availability, and — importantly for reading the statistics — means federal receipts capture only the value the plant adds, not the finished vehicle's full price.

2. What's inside — the four children and how they differ

The distinctive fact about 33621 is the contrast across its children. The table below is the heart of the primer; the rest expands on it. (Receipts are 2022 Economic Census; employment is 2023 County Business Patterns; concentration is 2022 Economic Census. Shares are of the NAICS 33621 level. HHI = Herfindahl-Hirschman Index, a standard concentration gauge where U.S. antitrust agencies treat ~1,500+ as "moderately concentrated" and ~2,500+ as "highly concentrated." CR4 = the combined revenue share of the four largest firms.)[1][2]

Five reads of that table:

1. Two families, roughly even by revenue — but the split is softer than it looks. The commercial half (bodies + trailers) is ~52% of level receipts; the recreational half (motorhomes + towables) is ~48%. By employment the commercial half is larger (~61% of jobs): RV plants generate more revenue per worker — higher average selling prices and more bought-in content flowing through — while the body count is understated because it excludes the chassis (Section 3). And the 48% figure overstates the consumer exposure, because 336214 bundles ordinary cargo, utility, and light-truck trailers with RVs; a landscaper's utility trailer answers to small-business capex, not to campground demand.[3]

2. The single biggest child is towables, not trucks. Travel Trailer & Camper (336214) alone is ~38% of level receipts — larger than either commercial child. The smallest, motorhomes, is barely a tenth. So a naive "motor vehicle body and trailer" reader who pictures work trucks is missing that the revenue center of gravity sits in the RV world.

3. Concentration is bimodal, and the level average hides it. The blended level HHI of 494 reads as "unconcentrated,"[1] but that is a statistical artifact of averaging two opposite structures. The commercial children are genuinely fragmented (bodies HHI ~238, trailers ~381); the RV children are oligopolies (motorhomes HHI ~2,023 with CR20 at 99.3%; towables CR4 ~71.4%). The step from CR4 to CR8 is the tell: in towables it is only 5 points (71.4% → 76.4%), meaning firms five through eight are already small — an oligopoly with a tail, not a broad top tier. In bodies the same step is 13 points (24.6% → 37.8%). Never quote the level HHI as if the industry were uniformly competitive.

4. In 2026 the children stopped moving in halves. The old framing — commercial down, recreational up — broke. Through May 2026 the commercial side was still soft (chassis sales −8.9%, trailer backlog −21%),[20][37] towables were down 17.2%, and motorhomes were up 11.8% on a shift toward smaller Class B and C coaches.[6] Two children that share a demand engine on paper delivered opposite results in the same five months. Read the level as four cycles, loosely grouped, not two.

5. Ownership dictates access. Where value concentrates and how you can own it differ by child. Motorhomes and towables are directly investable through two listed RV makers (Thor, Winnebago). Trailers offer exactly one pure-play stock (Wabash). Bodies offer no pure play at all — only slices inside diversified industrials or the private/private-equity route. This is the practical payoff of the whole primer (Section 4, Section 10).

What 33621 excludes (the neighbors that complete the picture): the complete self-powered vehicles — automobiles and light trucks (336110), heavy-duty trucks (336120) — and parts codes (metal stamping 336370, etc.). The chassis a 33621 plant mounts its body onto is built by one of those neighbors, and its value lands there, not here.[3]

3. How big it is

Federal ground-truth figures for NAICS 33621 (our ingested data):

So 33621 is a mid-sized manufacturing industry: roughly 2,200 plants, ~170,000 workers, and ~$72 billion of body-and-trailer shipments a year.[1][2] The rollup is unusually clean — the four children's establishment counts (855 + 569 + 71 + 704) and employment (58,318 + 45,403 + 11,862 + 54,952) sum exactly to the level totals, and receipts and payroll match to rounding. (The firm count, 1,880 at the level versus 1,911 summed across children — 781 + 497 + 58 + 575 — is slightly lower because a company operating in two of these industries is counted once at the level.)

Where it is. The two halves have very different maps. The recreational children are extraordinarily clustered: Indiana — effectively the Elkhart County area — builds roughly 86% of all RVs made in the U.S. and Canada,[48] and accounted for 67% of motorhome shipment value in the Census Bureau's industry analysis.[49] The commercial children are not concentrated that way; body and trailer plants sit near fleets, dealers, and chassis pools across many states. One Indiana labor market, weather event, or supplier cluster is therefore a level-wide risk for roughly half of receipts and almost none of the other half.

Undercount and scope caveats — read before comparing to any "market" figure:

• Bodies understate the vehicles they complete. The 336211 receipts count only the body, not the finished truck. A $70,000 delivery truck may carry a chassis worth more than the box on top; that chassis revenue lands with Ford, GM, Stellantis, or Freightliner, not in 33621. The economic footprint of the vehicles these plants finish is several times the body number. Separately, many small upfitters and truck-equipment distributors that finish vehicles are filed under wholesale, distribution, or repair codes, so the census undercounts who does body work. For the commercial half, treat the receipts as a floor.[3]
• Trailers understate U.S. demand — but for the opposite reason. Federal statistics measure U.S. production; a large share of trailers sold here are imported, chiefly from Mexico (roughly 72,000 van units in 2023 and 49,000 in 2024).[21] U.S. demand is materially larger than domestic shipments imply — the gap that drives the trade fight in Section 8.
• Towables (336214) overstate the RV slice. This child bundles ordinary cargo and utility trailers and truck caps with RVs, so its $27.6 billion runs higher than RV-only tallies (~$20.4 billion of 2025 RV value at retail, all types).[7] A landscaper's utility trailer and an Airstream share the code.
• 2022 was a peak. The Economic Census snapshot lands on a pandemic-boom year for RVs; motorhome and towable volumes fell hard in 2023–24 before stabilizing, so the RV receipts overstate the current run-rate.[5] The commercial trailer half, by contrast, was mid-downturn in 2025.
• The RV trade data is internally inconsistent, and both RV children flagged it. RVIA's 2025 year-end release carries headline totals of 342,220 RVs and 306,191 towables against line-item totals of 342,121 and 306,114, and reports motorhomes as 36,029 in prose versus 36,007 in the table.[5] The differences are small and unexplained; both child primers preserved rather than reconciled them, and so does this one.

Unlike sectors dominated by tiny informal operators, 33621 is captured well by federal statistics for its manufacturing core — these are real factories with payrolls. The pitfalls here are scope (body value vs. finished vehicle; trailers vs. RVs) and timing (which year), not hidden micro-operators.

4. The investable universe — where value concentrates

There is no single stock that is "NAICS 33621." Public exposure is scattered across four different structures, and — a useful quirk — a few companies straddle two of the children.

Recreational half (the directly investable one). Two U.S.-listed RV makers give clean, direct exposure to both RV children:

• Thor Industries (NYSE: THO) — world's largest RV maker, FY2025 net sales $9.58 billion, spanning both RV children: North American Towable was $3.785 billion of sales and North American Motorized $2.18 billion on 17,153 units.[8][9] Share: ~47.5% of U.S./Canada motorized retail registrations and ~38–39% of travel trailers and fifth-wheels.[8][9]
• Winnebago Industries (NYSE: WGO) — $2.80 billion FY2025 net revenues across Towable ($1.22 billion), Motorhome ($1.16 billion, 5,742 units), and Marine; ~15.2% U.S./Canada motorized share.[10][11][12]
• Forest River — the #2 RV maker, private inside Berkshire Hathaway (NYSE: BRK.B), which reported it at roughly 36% of the overall RV market and ~20.2% of motorized registrations; reachable only as an immaterial slice of Berkshire.[10][13]
• Four groups — Thor, Forest River, Winnebago, and the former REV organization now inside Terex — accounted for 89.5% of 2025 U.S./Canada motorized retail registrations.[10]
• To play RV demand without picking a builder: component suppliers LCI Industries (NYSE: LCII) — ~$4.1 billion revenue, ~44% of 2025 sales to North American RV OEMs, and $5,670 of content per travel trailer/fifth-wheel — and Patrick Industries (NASDAQ: PATK) — ~$3.8 billion revenue, ~45% from the RV end market — sell "content per RV" to every plant, and Camping World (NYSE: CWH) is the largest RV dealer at ~$6.4 billion of 2025 revenue.[14][15][16] Note the scale point: Camping World's single-company retail revenue is comparable to the entire motorhome child's factory receipts — different measures, but a fair indication of how much of the RV dollar sits downstream of the plant.

Commercial half (embedded and lopsided).

• Truck Trailer (336212) has essentially one pure-play: Wabash National (NYSE: WNC), a small-cap, deep-cyclical maker of dry vans, reefers, and tank trailers plus a parts-and-services arm — and even that is imperfect, since new trailers were only 65% of its ~$1.54 billion of 2025 revenue.[17][18] The rest of the top tier is private (Great Dane, Utility, Stoughton) or foreign-owned (Hyundai Translead, the #1 North American producer at 56,088 units in 2024 and ~39,900 in 2025, a Hyundai subsidiary building in Mexico; Vanguard, owned by China's CIMC).[19] The USITC identifies Great Dane and Wabash as the leading U.S. producers of van-type trailers.[22]
• Motor Vehicle Body (336211) has no pure-play. After 2025–26 consolidation the cleanest listed proxies are Terex (NYSE: TEX) — which absorbed REV Group (FY2025 net sales ~$2.46 billion) in a ~$9 billion deal that closed February 2, 2026[26][27] — and Aebi Schmidt (Nasdaq: AEBI) — which absorbed The Shyft Group's walk-in vans and service bodies on July 1, 2025, for ~$1.9 billion of combined pro-forma revenue.[29] Adjacent plays: Oshkosh (NYSE: OSK) for Pierce fire apparatus and McNeilus refuse bodies (its Vocational segment was 36% of consolidated 2025 sales),[31] Federal Signal (NYSE: FSS) for vocational/environmental bodies, Blue Bird (NASDAQ: BLBD) for school buses ($1.480 billion FY2025 net sales, $221.3 million adjusted EBITDA — the closest thing in the child to a pure play, but concentrated in one policy-sensitive niche),[33] and Wabash again for truck bodies. The largest concentrated body owner, J.B. Poindexter & Co. (Morgan, Reading; ~$2.5 billion revenue, ~8,500 employees, with Morgan at roughly 45% of the medium-duty body market), is private,[34] as is service-body leader Knapheide, family-owned since 1848.[35]

The cross-over names worth noting: Wabash sits in both commercial children (bodies and trailers). Terex now spans bodies (fire, ambulance, refuse) and motorhomes — REV's RV segment alone was $649 million of FY2025 net sales.[27] So the tidy four-child map blurs at the level of the actual listed companies — another reason to think in terms of which demand engine you are buying, not which NAICS box.

Bottom line. If you want direct, liquid exposure, the recreational half (Thor, Winnebago, plus suppliers) is where the public market actually lives. The commercial half is a narrow one-stock trailer play (Wabash) plus body slices buried inside diversified industrials — with the private/private-equity route doing much of the heavy lifting.

5. How the money works

All four children run the same basic model — a build-to-order assembly business that turns bought-in materials and a purchased chassis into a body, trailer, or RV at a price above cost — but the profit levers differ by half.

Shared mechanics (all four):

• Value-add on someone else's chassis/components. The costliest part is bought in, keeping working capital lighter but tying output to chassis availability — no frame, no build. Chassis shortages idled body and motorhome plants in 2021–23 even with full order books, and Winnebago still flags a small motorhome-chassis supplier group as a live constraint.[11]
• Capacity utilization is the whole game. Fixed factory costs are spread over units built; profitability swings with volume far more than price. Running lines full is the difference between healthy and thin margins — the operating leverage that makes every child cyclical.
• Input-cost lag. Steel, aluminum, lumber, resins, and purchased components (axles, appliances, lift gates, refrigeration units) drive cost. Prices are often quoted at order and delivered months later, so a steel or aluminum spike compresses margins until the order book reprices. Blue Bird is the counter-example that proves the mechanism: its cost of goods sold fell to 79.5% of FY2025 sales from 81.0% because pricing finally ran ahead of inflation.[33]
• Mix lifts margin. Commodity dry vans and entry campers earn least; engineered vocational/emergency bodies and luxury coaches earn most.
• Concentrated buyers on both sides. This is not a diffuse customer base. Wabash's five largest customers were ~35% of 2025 sales;[18] Camping World's operating business FreedomRoads alone was ~14% of Thor's fiscal 2025 sales and receivables;[9] and two floorplan lenders held roughly 51% of Winnebago's financed dealer-inventory dollars at fiscal year-end.[11] A handful of decisions — by fleets, by dealer groups, by lenders — moves the level's output.

What fiscal 2025 revealed — one model, four different outcomes. Because all four children report through a handful of listed parents, the segment disclosures line up unusually well, and they show how far apart the children ran in a single year:

• Towables earned the most. Thor's North American Towable segment turned $3.785 billion of sales into $497 million of gross profit — a 13.1% gross margin, with pretax income around 6.5% of sales.[9] Winnebago's smaller towable book ran a 6.0% operating margin, down from 7.8%.[12]
• Motorhomes earned less, and at one maker nothing. Thor's North American Motorized gross margin fell to 9.7% from 11.4%, with pretax income about 3.9% of sales;[8] Winnebago's Motorhome segment swung to a $7.3 million operating loss (−0.6%) from $52.9 million of operating income (4.1%) a year earlier, as volume deleverage and discounting overwhelmed a richer mix.[11]
• Commodity trailers earned almost nothing. Wabash's Transportation Solutions gross margin collapsed from 12.4% to 1.9%, and the segment posted an operating loss of roughly −12%.[17][18]
• Engineered bodies earned most consistently. REV's Specialty Vehicles segment (fire, ambulance, terminal trucks) reported a 12.5% adjusted EBITDA margin.[28]
• The aftermarket beat all of them. Wabash's Parts & Services gross margin was 18.6% in 2025 (23.1% in 2024) and the segment held a positive ~8–11% operating margin while new-trailer assembly lost money.[17][18]

The lesson for the level: mix and aftermarket, not scale, separate the winners. The highest-margin businesses inside 33621 are the engineered, low-volume vocational bodies and the parts-and-service pools attached to every child — not the high-volume commodity boxes at either end.

Backlogs are pointing in opposite directions, which is itself a fair summary of the level. Oshkosh carried roughly $5.3 billion of fire-apparatus backlog with waits reaching ~4.5 years,[32] and REV closed fiscal 2025 with $4.402 billion of Specialty Vehicles backlog;[28] Thor's North American Motorized backlog rose 29.3% to $1.005 billion as dealers restocked;[8] while Wabash's backlog fell 40%, from $1.17 billion to $705 million, and the industry's unit backlog entered 2026 at roughly 84,500 units, about 21% below a year earlier.[18][20] Treat all of it as softer than in most capital-goods industries: REV warns orders may be cancelled or postponed, RV dealer orders can often be cancelled without penalty, and Wabash's customers may change quantity, specification, or timing.[8][18][28]

Where the two halves diverge on channel:

• Commercial half — watch the order book. Trailers are sold through dealers, direct fleet orders (a single carrier may order thousands at once), and leasing companies; the tells are monthly net orders, backlog, and the backlog-to-build ratio.[20]
• Recreational half — watch the dealer channel and floor-plan financing. RV makers book revenue when a unit ships to a dealer, not when a consumer buys it. Dealers hold inventory on floor-plan loans (bank financing secured by units on the lot). The central dynamic is the gap between wholesale shipments and retail registrations: over-shipping in 2021–22 forced destocking and heavy discounting in 2023–24 that hammered margins.[9][11] Shipments can diverge from real demand for a year or more, so watch the two together, not either alone.

6. What drives demand

The four children answer to two different demand engines — with the 2026 caveat from Section 2 that even children sharing an engine can move apart.

Commercial half — the goods economy:

• Freight volumes and rates. Dry vans, reefers, and freight bodies track for-hire trucking and fleet capital spending. A freight downturn (2023–25) collapses orders — visible in Wabash revenue falling from ~$1.95B (2024) to ~$1.54B (2025).[17] Trailers are the purest, most amplified read of the freight cycle.
• Chassis supply as a demand proxy. NTEA reported U.S./Mexico commercial-truck chassis sales down 8.9% year over year in April 2026 — a direct read on how much body work is being fed into the plants.[37]
• E-commerce / last-mile delivery. Structural growth in delivery vans and step-van bodies (~500,000 U.S. commercial vans a year).
• Construction and vocational work. Dump, service, and utility bodies rise with construction and infrastructure — and this is where 336214's cargo/utility-trailer tail quietly belongs too.
• Municipal / public-safety budgets. Fire trucks, ambulances, street sweepers, and school buses are funded by state, local, and federal grants — steadier and more counter-cyclical than freight, which is why the body child held up better than trailers in 2025.[27] Policy is a live variable: Congress directed EPA to provide $5 billion over fiscal 2022–2026 for clean and zero-emission school-bus replacement, but EPA was revamping the program without a next funding round announced, leaving mix and timing exposed.[50]

Recreational half — the discretionary consumer:

• Interest rates and credit — the single biggest lever, twice over. RVs are financed purchases (2025 loan APRs ~9.5–13.5%, with subprime buyers near 20% and largely priced out), and dealer floor-plan costs also rise with rates, so higher-for-longer squeezes buyer affordability and channel inventory simultaneously.[46] Falling rates are the industry's main hoped-for tailwind.
• Consumer confidence and the macro cycle. An RV is a deferrable luxury — cut first in downturns, bought back fast in recoveries. Towables, being cheaper, hold up better than motorhomes when money is tight, which is why the 2026 pattern (motorhomes up, towables down) is worth watching rather than assuming.[6]
• Demographics — a genuine tailwind, but the children disagree on its size. Both RV primers agree the buyer base is broadening and getting younger (median owner age fell from 53 in 2021 to 49 in 2025) and that camping participation is large and growing.[44][45] They do not agree on the installed base: the towables primer reads RVIA's 2025 Go RVing profile as ~8.1 million U.S. households owning an RV, while the motorhome primer reads RVIA's material as ~11.2 million owning households with 16.9 million more expressing strong interest.[44][45] RVIA materially changed the survey methodology in 2025, so its counts are not comparable with earlier series.[45] Treat the installed base as "roughly 8–11 million households and broadening," not as a precise number — and do not build a model that depends on the difference.

Common to both: fleet and installed-base replacement cycles put a recurring floor under demand; electrification (EV delivery bodies, zero-emission chassis mandates) is an emerging product-mix and supply factor for all four.

7. Regulation

Every child is regulated as a vehicle, not as housing or as a rate-regulated utility — so there is no rate base, license, or franchise that limits who may compete. Compliance is a discipline, not a moat.

• Commercial half — final-stage / multistage manufacturing. When a body builder mounts a body on an incomplete chassis it becomes the vehicle's final-stage manufacturer and must certify the finished truck meets all applicable FMVSS (Federal Motor Vehicle Safety Standards), enforced by NHTSA (National Highway Traffic Safety Administration) under 49 CFR (Code of Federal Regulations) Part 568 — carrying recall and defect-remedy obligations with it; the NTEA (The Work Truck Association) shepherds members through it.[36] Trailers face a lighter regime, but NHTSA's 2022 upgrade to rear underride-guard standards (FMVSS 223/224) added content, and a possible future side-underride mandate would add cost and weight per trailer.[38] Trailers currently face no federal fuel-economy mandate — courts vacated the EPA's GHG Phase 2 trailer rules after the industry argued trailers are not "motor vehicles," and the 2024 Phase 3 rule likewise excludes them.[38]
• Recreational half — vehicle safety plus industry self-policing. Motorhomes and towables fall under NHTSA/FMVSS for lighting, brakes, and tires, but construction, LP-gas, electrical, and fire safety run on voluntary consensus standards (NFPA 1192, from the National Fire Protection Association) enforced by the RVIA (RV Industry Association) through unannounced factory inspections — more than 2,000 a year, on roughly an eight-week cycle; the RVIA seal is the market's quality gate. RVs are exempt from the federal HUD (Department of Housing and Urban Development) manufactured-home code.[40] A live constraint: CARB (California Air Resources Board) Advanced Clean Trucks rules require chassis makers to sell rising shares of zero-emission vehicles, and with no viable zero-emission motorhome chassis yet, some suppliers have paused conventional motorhome-chassis sales in California and states following its rules — a real near-term supply pinch.[41]
• Environmental compliance cuts across both halves, in different forms. Body plants sit under EPA Clean Air Act controls on painting and coating (the automobile and light-truck surface-coating NESHAP covers toluene, xylene, glycol ethers, and methanol); RV and camper plants sit under EPA's TSCA Title VI formaldehyde rules for hardwood plywood, MDF, and particleboard, whose compliance material names travel-trailer and camper manufacturers explicitly as affected fabricators.[50] Same regulator, opposite bill of materials.
• Trade and tariffs cut across both halves. Section 232 tariffs on steel and aluminum rose from 25% to 50% in mid-2025 — Terex disclosed the increase directly — and were extended in September 2025 to softwood lumber and the imported lauan plywood the RV industry relies on, raising input costs across all four children.[30][42] Separately, the trailer child is the subject of an active antidumping/countervailing-duty proceeding (Section 8).

8. Consolidation

The four children sit at very different points on the consolidation curve, which is exactly what their concentration numbers say.

• Motor Home (336213) is already an oligopoly — CR4 ~82.5%, CR8 ~94.8%, HHI ~2,023[1] — built by acquisitive families: Thor (Jayco, Erwin Hymer, Tiffin), Winnebago (Grand Design, Newmar), and Berkshire's Forest River. Four groups now hold 89.5% of U.S./Canada motorized retail registrations.[10] Little further consolidation is possible at the top; the recent move was REV Group's RV brands folding into Terex on February 2, 2026, which removed REV as a standalone listed RV exposure.[26][27]
• Travel Trailer & Camper (336214) is an oligopoly on top of a fragmented tail — CR4 ~71.4%, CR8 only ~76.4%, HHI suppressed in federal data.[1] Patrick Industries estimates the three largest groups at ~86% of 2025 towable retail unit share, and Berkshire puts Forest River alone at ~36% of the overall RV market.[13][14] Brand proliferation badly overstates the competition: Thor counts roughly 80 North American RV manufacturers, but the top three groups build the vast majority of units.[9] The long tail of small trailer welders is the genuinely fragmented remainder.
• Truck Trailer (336212) is consolidated but not concentrated — a top five (Hyundai Translead, Great Dane, Utility, Wabash, Stoughton) builds most units, yet HHI is only ~381.[1][19] Its defining 2020s story is trade, and that story has now moved from petition to preliminary duty. Following November 2025 antidumping and countervailing-duty petitions on van-type trailers from Canada, China, and Mexico (and February 2025 petitions on intermodal chassis),[21] the USITC found a reasonable indication of material injury,[22] and on July 30, 2026 Commerce announced preliminary affirmative antidumping determinations: an "all others" margin of 4.29% for Canada; an adjusted all-others cash-deposit rate of 7.10% for Mexico (Hyundai de México 8.35%, Utility Trailer de México 2.43%); and a preliminary adjusted antidumping rate of 130.76% for China, with preliminary countervailing-duty rates including 82.37% for specified CIMC entities.[23][24] These are preliminary, not final. If duties land at or near these levels they would reshape share and push production onshore — the single biggest structural swing factor for this child, and Hyundai has already signaled plans to build in the U.S.[19][23]
• Motor Vehicle Body (336211) is the fragmented roll-up frontier — CR4 ~24.6%, HHI ~238[1] — a few national brands plus hundreds of regional shops, a structure REV itself described as "a highly fragmented market containing many small producers."[28] It is the industry's most active consolidation theater: J.B. Poindexter assembled a ~$2.5B body group by acquisition;[34] Wabash bought Supreme; and 2025–26 brought the two biggest moves, Shyft into Aebi Schmidt (July 2025) and REV Group into Terex (February 2026), each folding a body business into a larger specialty-vehicle platform for scale, purchasing power, and cross-selling.[26][29]

The through-line: competitive advantage across all four accrues to scale (chassis-pool relationships with OEMs, national distribution and upfitting footprint), engineering depth in high-mix niches (fire, ambulance, luxury coaches), and aftermarket networks. Note that the supplier and dealer sides are consolidating too — LCI and Patrick on components, Camping World in retail — so bargaining power is contested up and down the chain, not just among the builders.[14][15][16] Expect continued roll-up of the fragmented commercial-body tail and steady, quieter consolidation elsewhere.

9. Risks

Shared across the industry:

• Deep cyclicality. Every child has high operating leverage; a downturn in its demand engine turns thin margins into outright losses. Fiscal 2025 produced an operating loss in Wabash's trailer segment and in Winnebago's motorhome segment in the same year.[11][17]
• Chassis / component dependence. Output is hostage to a few automakers for chassis; shortages or emissions-driven allocation can idle plants regardless of demand.[11][41]
• Input-cost and tariff whipsaw. Steel, aluminum, and imported wood price spikes compress margins given order-to-delivery pricing lags; the Section 232 step from 25% to 50% raised the input-cost floor for all four children.[30][42]
• Labor — and it is measurably more dangerous work than the sector average. Skilled welders and assemblers are scarce in a labor-intensive build process, and BLS put the 2024 recordable injury and illness rate at 5.1 cases per 100 full-time workers for NAICS 3362 and 6.0 for the towables child specifically, against 3.2 for transportation-equipment manufacturing overall.[47] Elkhart's clustering magnifies both shortage in upcycles and layoffs in destocking.
• Integration risk. The 2025–26 mega-mergers (Terex/REV, Aebi Schmidt/Shyft) must deliver promised synergies; specialty-vehicle roll-ups have a mixed record.

Specific to the commercial half:

• Backlog normalization. Extraordinary post-2021 backlogs (Oshkosh ~$5.3 billion in fire apparatus, REV $4.402 billion in specialty vehicles) will unwind; a return to normal lead times could pressure pricing and reveal peak-added capacity, and REV explicitly warns those orders may be cancelled or postponed.[28][32]
• Product-liability litigation. As certified final-stage manufacturers, body and trailer builders carry recall and jury risk — a Missouri jury hit Wabash with a $462 million underride verdict in September 2024 even though the guard met the then-current federal minimum.[39] The judgment was subsequently reduced: Wabash recorded a $450 million loss in 2024 general-and-administrative expense and a $418 million gain in 2025 following the reduction.[18] The exposure is real but the headline number was not the final cost.
• Trough balance-sheet stress. Small-cap makers may have to raise capital at the bottom — Wabash floated $100 million of convertible notes in 2026, leveraging into the cycle.[17]
• Import competition / trade outcome. Absent final duties, low-cost Mexican and Chinese-owned trailer supply pressures U.S. share and pricing; if the preliminary determinations hold, fleet costs rise instead.[21][23]

Specific to the recreational half:

• Interest-rate and confidence relapse. A higher-for-longer environment hits buyer affordability and dealer floor-plan costs at once.[46]
• Channel whipsaw. Wholesale shipments can diverge from retail registrations, forcing destocking and discounting — and dealer-financing concentration (two lenders behind ~51% of Winnebago's financed dealer inventory) means a credit shock transmits fast.[11]
• Geographic single point of failure. ~86% of North American RV output in one Indiana region concentrates labor, weather, infrastructure, and supply-chain risk for half the level.[48]
• Concentration risk for owners. With so few RV makers, one player's share-grab or a supplier stumble reverberates industry-wide; RVIA cut its 2026 wholesale projection to a ~314,000-unit median (roughly −8% versus 2025), and shipments were already down 14.4% year over year through May 2026.[6][43]

10. How to invest, and the outlook

Public-market routes — pick your demand engine first, then the child.

• A discretionary-consumer / rate-cycle bet → the recreational half: Thor (THO) and Winnebago (WGO) are the direct RV makers, each spanning both RV children; LCI (LCII) and Patrick (PATK) capture "content per RV" across every builder with less single-name risk; Camping World (CWH) is the retail/service angle, where service and finance income are less cyclical than new-unit sales.[14][15][16] All move together and violently, so entry point and position sizing matter more than stock selection.
• A freight-cycle bet → the truck-trailer child: Wabash (WNC) is the only listed pure play — a small-cap, deep-cyclical call on U.S. freight, watched via monthly trailer orders and backlog, and diluted by the ~35% of 2025 revenue that is not new trailers.[18][20] Broader exposure comes through customers (trucking fleets) and suppliers (steel, aluminum, axles).
• A commercial-body / vocational bet → no pure play; the cleanest listed proxies after the 2025–26 reshuffle are Terex (TEX) and Aebi Schmidt (AEBI), with Oshkosh (OSK), Federal Signal (FSS), and Blue Bird (BLBD) adjacent. In each case the body business is one piece of a larger industrial — Oshkosh's Vocational segment was 36% of 2025 sales; Blue Bird is the nearest thing to a pure play but is really a school-bus policy bet.[31][33]

Private-market routes — where much of the commercial half actually trades. The body child is private-heavy and fragmented, making it the natural home for private-equity buy-and-build: the largest concentrated owner (J.B. Poindexter) and the service-body leader (Knapheide) are private, and the regional-shop tail is a roll-up hunting ground.[34][35] In trailers, most producers are private or foreign-owned, so private capital participates mainly through dealerships, leasing/rental fleets, and component suppliers rather than the OEMs; trailer leasing is a distinct, steadier cash-flow business than manufacturing.[18] In RVs the big brands are unbuyable, but adjacent campground/RV-park real estate, dealer roll-ups, and the supplier base monetize the same demographic tailwind with a different risk profile. Across all four, the recurring diligence trap is the same: revenue reported at peak backlog and utilization should not be capitalized as if it were recurring, and reported revenue may or may not include the purchased chassis.

Near-term outlook (forward-looking). The children are on different clocks, and 2026 has pulled them further apart. The commercial half hinges on the freight-cycle turn (December 2025 orders surged and backlog began firming, but builds hit their lowest level since 2010 and the entering-2026 backlog was 21% lighter),[20] on whether Commerce's preliminary duties become final determinations later in 2026,[23][24] and on whether the mega-mergers convert combined body operations into promised synergies — set against elevated but eventually-normalizing emergency-vehicle backlogs. The recreational half is now two stories: motorhomes running up double digits on Class B and C demand, towables running down 17% against a ~−8% full-year forecast.[6][43] Both still hinge on the rate path, the wholesale-vs-retail destock/restock signal, tariffs on steel/aluminum/lumber, and the younger-buyer demographic that, if it holds, lengthens the recovery beyond one rate cycle.

In short: NAICS 33621 is one industry statistic covering two economies — a ~$72 billion, ~170,000-worker manufacturing base split almost evenly between work vehicles that ride the freight-and-construction cycle and recreational vehicles that ride the rate-and-confidence cycle. Its blended "unconcentrated" HHI masks a bimodal reality: fragmented, consolidating commercial-body and trailer businesses on one side; RV oligopolies clustered in one Indiana county on the other. Within it, the money is made in engineered low-volume niches and aftermarket service, not in commodity boxes at either end. For an investor, the practical move is not to buy "the industry" but to decide which demand engine you want, then choose the child — and the ownership route — that gives you the cleanest exposure to it.

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Sources

1. U.S. Census Bureau. "2022 Economic Census — Industry concentration and receipts, NAICS 33621 and children 336211/336212/336213/336214 (receipts, firms, CR4/CR8/CR20/CR50, HHI)." census.gov. https://www.census.gov/programs-surveys/economic-census.html
2. U.S. Census Bureau. "County Business Patterns (CBP), 2023 — NAICS 33621 and children (establishments, employment, annual and Q1 payroll)." census.gov. https://www.census.gov/programs-surveys/cbp.html
3. U.S. Census Bureau. "2022 NAICS Definitions: 336211, 336212, 336213, 336214 (scope and exclusions)." census.gov. https://www.census.gov/naics/?input=33621&year=2022
4. U.S. Small Business Administration. "Table of Small Business Size Standards (NAICS 336211/336212/336214 = 1,000 employees; 336213 = 1,250), 2023." sba.gov. https://www.sba.gov/document/support-table-size-standards
5. RV Industry Association. "RV Shipments End 2025 with 342,220 Units, Modest 2.5% Growth over 2024" (motorhomes ~36,000, +3.3%; towable line items totaling 306,114; internal headline-vs-line-item discrepancies). 2025. https://www.rvia.org/reports-trends/rv-shipment-reports/2025-12/rv-shipments-end-2025-342220-units-modest-25-growth-over-2024
6. RV Industry Association. "RV Shipments 22,900 in May" (May 2026 report: total RV shipments −14.4% y/y, towables −17.2%, motorhomes 17,739 units +11.8%). 2026. https://www.rvia.org/reports-trends/rv-shipment-reports/2026-05/rv-shipments-22900-may
7. RV PRO / RV Industry Association. "2025 Industry Profile and Market Reports" (towables ~88% of RV units; 2025 RV retail value ~$20.4 billion). 2025. https://www.rvia.org/rv-industry-profile
8. Thor Industries, Inc. "THOR Industries Announces Fiscal 2025 Fourth Quarter and Full Year Results" (net sales $9.58B; North American Motorized $2.18B on 17,153 units, 9.7% gross margin, backlog +29.3% to $1.005B). 2025. https://www.globenewswire.com/news-release/2025/09/24/3155308/0/en/THOR-Industries-Announces-Fiscal-2025-Fourth-Quarter-and-Full-Year-Results.html
9. Thor Industries, Inc. Form 10-K, fiscal year ended July 31, 2025 (North American Towable $3.785B and 13.1% gross margin; ~47.5% motorized and ~38–39% travel-trailer/fifth-wheel share; FreedomRoads ~14% of sales; ~80 North American RV manufacturers). SEC EDGAR. https://www.sec.gov/Archives/edgar/data/730263/000073026325000019/tho-20250731.htm
10. Thor Industries, Inc. Q2 FY2026 Investor Presentation (U.S./Canada motorized retail registration share by group; four groups 89.5%). 2026. https://www.sec.gov/Archives/edgar/data/730263/000073026326000008/thoq2fy26-investorpresen.htm
11. Winnebago Industries, Inc. Form 10-K, fiscal year ended August 30, 2025 (net revenues $2.80B; Motorhome segment $1.16B, 5,742 units, −0.6% operating margin; two floorplan lenders ~51% of financed dealer inventory; chassis supplier concentration; tariff exposure). SEC EDGAR. https://www.sec.gov/Archives/edgar/data/107687/000010768725000034/wgo-20250830.htm
12. Winnebago Industries, Inc. Form 8-K, Q4 FY2025 earnings release (Towable RV segment $1.22B revenue, $72.7M operating income, 6.0% operating margin). 2025. https://www.sec.gov/Archives/edgar/data/107687/000010768725000032/exh9912025q4earningsrelease.htm
13. Berkshire Hathaway Inc. Form 10-K, FY2025 (Forest River ~36% of the overall RV market; brands). 2025. https://www.berkshirehathaway.com/2025ar/202510-k.pdf
14. Patrick Industries, Inc. Form 10-K, FY2025 (top three RV groups ~86% of 2025 towable retail unit share; ~45% of sales from the RV end market; ~$3.8B revenue). SEC EDGAR. https://www.sec.gov/Archives/edgar/data/76605/000007660526000013/patk-20251231.htm
15. LCI Industries. Form 10-K, FY2025 (~$4.1B revenue; $5,670 content per travel trailer/fifth wheel; ~44% of 2025 sales from North American RV OEMs). SEC EDGAR. https://www.sec.gov/Archives/edgar/data/763744/000076374426000011/lcii-20251231.htm
16. Camping World Holdings, Inc. Form 10-K, FY2025 ($6.369B total revenue; $2.761B new vehicles; $1.970B used vehicles). SEC EDGAR. https://www.sec.gov/Archives/edgar/data/1669779/000110465926021548/cwh-20251231x10k.htm
17. GlobeNewswire / Wabash National. "Wabash Announces Fourth Quarter and Full Year 2025 Results" (FY2025 revenue ~$1.54B vs. ~$1.95B in 2024; Transportation Solutions operating loss; Parts & Services operating margin; $100M convertible notes). 2026. https://www.globenewswire.com/news-release/2026/02/04/3231876/0/en/Wabash-Announces-Fourth-Quarter-and-Full-Year-2025-Results.html
18. Wabash National Corp. Form 10-K, FY2025 (new trailers 65% of revenue; backlog $1.17B → $705M; Transportation Solutions gross margin 12.4% → 1.9%; Parts & Services gross margin 23.1% → 18.6%; top five customers ~35% of sales; $450M litigation loss 2024 and $418M gain 2025; supplier and labor risk). SEC EDGAR. https://www.sec.gov/Archives/edgar/data/879526/000087952626000036/wnc-20251231.htm
19. ACT Research, via Commercial Carrier Journal. "Major trailer producers and 2024–2025 unit output/share (Hyundai Translead 56,088 units in 2024 and ~39,900 in 2025, ~23% U.S. share; Great Dane; Utility; Wabash; Stoughton; Vanguard/CIMC); 2025 industry output 200,485 units vs. 245,344 in 2024." 2025–2026. https://www.ccjdigital.com/trucks/article/15742636/could-hyundai-transleads-dominance-be-a-glimpse-into-the-future-of-trucking; https://www.actresearch.net/resources/knowledge-center/who-are-the-major-players-in-the-trailer-market-and-what-are-their-sales
20. FleetOwner / Truck Parts & Service (citing ACT Research and FTR). "U.S. trailer orders and backlog, 2025 year-end (backlog ~84,501 units, −21% y/y; December builds lowest since 2010; December orders surge)." 2025–2026. https://www.fleetowner.com/equipment/article/55352048/december-us-trailer-orders-surge-but-face-tariff-volatility-in-2026; https://www.truckpartsandservice.com/trucks-trailers/trailers/article/15818237/trailer-industry-backlog-growth-signals-possible-2026-recovery
21. U.S. Federal Register; Akin Gump. "Antidumping and countervailing-duty petitions: van-type trailers and subassemblies from Canada, China, and Mexico (Nov. 2025); intermodal chassis from Mexico, Thailand, Vietnam (Feb. 2025); import volumes ~72,000 units 2023 and ~49,000 units 2024." 2025–2026. https://www.federalregister.gov/documents/2025/11/25/2025-20933/van-type-trailers-and-subassemblies-from-canada-china-and-mexico; https://www.akingump.com/en/insights/alerts/new-antidumping-and-countervailing-duty-petitions-on-van-type-trailers-and-subassemblies-thereof-from-canada-mexico-and-china
22. U.S. International Trade Commission. Publication 5704, "Van-Type Trailers and Subassemblies Thereof from Canada, China, and Mexico" (preliminary injury determination; Great Dane and Wabash identified as leading U.S. producers). 2026. https://www.usitc.gov/sites/default/files/publications/701_731/pub5704.pdf
23. U.S. Dept. of Commerce, International Trade Administration. "Preliminary Affirmative Determinations, Antidumping Duty Investigations: Van-Type Trailers and Subassemblies from Canada and Mexico" (all-others: Canada 4.29%, Mexico 7.10%; Hyundai de México 8.35%; Utility Trailer Manufacturing de México 2.43%). July 30, 2026. https://www.trade.gov/preliminary-affirmative-determinations-antidumping-duty-investigations-van-type-trailers-and-0
24. U.S. Dept. of Commerce, International Trade Administration. "Preliminary Affirmative Determinations: Van-Type Trailers from China" (AD rate 130.76%; CVD rate 82.37% for specified CIMC entities). July 2026. https://www.trade.gov/preliminary-affirmative-determinations-antidumping-duty-investigations-van-type-trailers-and; https://www.trade.gov/preliminary-affirmative-determinations-countervailing-duty-investigations-van-type-trailers-and-0
25. U.S. Census Bureau. 2022 Commodity Flow Survey. "Trucks hauled 8.3 billion tons (68.1% of tonnage) and $13.2 trillion of goods (73.5% of value)." 2025. https://www.census.gov/newsroom/press-releases/2025/cfs-shipments-of-goods.html
26. PRNewswire / Terex Corporation. "Terex Corporation and REV Group Complete Merger" (closed February 2, 2026). 2026. https://www.prnewswire.com/news-releases/terex-corporation-and-rev-group-receive-stockholder-approval-for-merger-302673139.html
27. Business Wire. "REV Group, Inc. Reports Strong Fiscal 2025 Fourth Quarter and Full Year Results" (FY2025 net sales ~$2.46B; RV segment $649M). 2025. https://www.businesswire.com/news/home/20251209516231/en/REV-Group-Inc.-Reports-Strong-Fiscal-2025-Fourth-Quarter-and-Full-Year-Results
28. REV Group, Inc. Form 10-K, fiscal year ended October 31, 2025 (Specialty Vehicles backlog $4.402 billion and 12.5% adjusted EBITDA margin; "highly fragmented market"; commodity inputs; backlog cancellation and skilled-labor risk). SEC EDGAR. https://www.sec.gov/Archives/edgar/data/1687221/000119312525313470/revg-20251031.htm
29. PRNewswire. "The Shyft Group and Aebi Schmidt Group Announce Successful Completion of Merger, Creating Global Specialty Vehicle Leader" (closed July 1, 2025; ~$1.9B combined pro-forma revenue). 2025. https://www.prnewswire.com/news-releases/the-shyft-group-and-aebi-schmidt-group-announce-successful-completion-of-merger-creating-global-specialty-vehicle-leader-302495121.html
30. Terex Corporation. Form 10-K, fiscal year ended December 31, 2025 (U.S. Section 232 steel tariff increased from 25% to 50% during 2025; Heil refuse bodies). SEC EDGAR. https://www.sec.gov/Archives/edgar/data/97216/000009721626000035/tex-20251231.htm
31. Oshkosh Corporation. Form 10-K, fiscal year ended December 31, 2025 (Vocational segment 36% of consolidated 2025 sales; Pierce and McNeilus). SEC EDGAR. https://www.sec.gov/Archives/edgar/data/775158/000119312526054061/osk-20251231.htm
32. Heavy Vehicle Inspection / Firehouse. "Fire Trucks Comparison Guide 2025; Oshkosh/Pierce fire-apparatus backlog (~$5.3 billion) and lead times (~4.5 years)." 2025. https://heavyvehicleinspection.com/equipment/fire-trucks-comparison-guide
33. Blue Bird Corporation. "Fiscal 2025 Fourth Quarter and Full Year Results" (net sales $1.480B; adjusted EBITDA $221.3M; cost of goods sold 79.5% of sales vs. 81.0%). SEC EDGAR. https://www.sec.gov/Archives/edgar/data/1589526/000158952625000099/a2025q4resultsreleaseex991.htm
34. FleetOwner. "JB Poindexter & Co. at 40: How the manufacturing conglomerate is shaping trucking" (~$2.5B revenue, ~8,500 employees; Morgan ~45% of the medium truck-body market). 2024. https://www.fleetowner.com/equipment/article/55281061/jb-poindexter-co-at-40-how-the-manufacturing-conglomerate-is-shaping-trucking
35. The Knapheide Manufacturing Company. "Truck Bodies / Work Trucks" and "Knapheide Celebrates 175 Years" (family-owned since 1848; service, utility, and mechanics bodies; distributor network). knapheide.com. https://www.knapheide.com/truck-bodies/; https://www.knapheide.com/blog/knapheide-celebrates-175-years/
36. NTEA — The Work Truck Association. "Multistage Vehicle Certification" (final-stage manufacturer, FMVSS, 49 CFR 568). ntea.com. https://www.ntea.com/multistage-vehicle-certification
37. NTEA — The Work Truck Association. "Market Data / Industry Statistics" (U.S./Mexico commercial-truck chassis sales −8.9% year over year, April 2026). ntea.com. https://www.ntea.com/data-reports/market-data-industry-statistics
38. U.S. NHTSA; Federal Register; Trucking Info. "Final rule upgrading FMVSS Nos. 223/224 rear impact (underride) guards, July 2022; IIJA-directed side-underride research; GHG Phase 2 trailer provisions vacated and Phase 3 excludes trailers." 2021–2024. https://www.nhtsa.gov/sites/nhtsa.gov/files/2022-06/Final-Rule-FMVSS-223-224-Rear-impact-protection-web.pdf; https://www.truckinginfo.com/142791/court-decision-puts-ghg-phase-2-rules-for-trailers-on-hold
39. Missouri Lawyers Media; Trailer Body Builders. "St. Louis jury returns $462M verdict ($12M compensatory, $450M punitive) against Wabash National in fatal rear-underride case, Sept. 2024." 2024. https://molawyersmedia.com/2024/09/25/jury-returns-462m-verdict-in-underride-crash-that-killed-two-fathers/
40. National Fire Protection Association. "NFPA 1192, Standard on Recreational Vehicles"; RV Industry Association standards, inspection program, and HUD manufactured-home exemption. 2025–2026. https://www.nfpa.org/product/nfpa-1192-standard/p1192code; https://www.rvia.org/standards-regulations
41. RV Industry Association. "Impact of CARB's ACT Regulation On Motorhomes: What You Need To Know." 2024. https://www.rvia.org/news-insights/impact-carbs-act-regulation-motorhomes-what-you-need-know
42. RV Industry Association. "Latest Tariff Developments — Section 232 steel/aluminum 25% to 50%, softwood lumber and lauan plywood." 2025. https://www.rvia.org/news-insights/latest-tariff-developments
43. RV Industry Association. "RV RoadSigns Quarterly Forecast — 2026 wholesale shipments (~314,000-unit median)." 2026. https://www.rvia.org/rv-roadsigns-quarterly-forecast
44. RV Industry Association. "2025 Go RVing RV Owner Demographic Profile" (median owner age 53 in 2021 to 49 in 2025; owning-household counts). 2025. https://www.rvia.org/2025-go-rving-rv-owner-demographic-profile
45. RV Industry Association / Ipsos. "RV Ownership Evolves: Younger, More Diverse and More Engaged" (2025 methodology change; owning and intending households; median ~30 days of annual use). 2025. https://www.rvia.org/news-insights/rv-ownership-evolves-younger-more-diverse-and-more-engaged
46. Bish's RV. "RV Industry Market Update — Fall 2025" (2025 RV loan APRs ~9.5–13.5%, subprime near 20%; floorplan financing; affordability shift). 2025. https://www.bishs.com/blog/rv-industry-market-update-fall-2025/
47. U.S. Bureau of Labor Statistics. "Table 1. Incidence rates of nonfatal occupational injuries and illnesses by industry, 2024" (NAICS 3362 = 5.1; NAICS 336214 = 6.0; transportation equipment manufacturing = 3.2 per 100 full-time workers). bls.gov. https://www.bls.gov/web/osh/table-1-industry-rates-national.htm
48. RVBusiness / Made in CA. "Indiana produces ~86% of North American RVs; the Elkhart cluster." 2025. https://rvbusiness.com/rvia-industry-profile-details-production-shipment-stats/
49. RV PRO, "Running Out of Room in the 'RV Capital of the World'"; U.S. Census Bureau, "Recreational Vehicle: A Way to See America from the Safety of Your Own Home" (Indiana 67% of motorhome shipment value). 2020–2024. https://rv-pro.com/features/running-out-of-room-in-the-rv-capital-of-the-world/; https://www.census.gov/library/stories/2020/09/recreational-vehicle-a-way-to-see-america-from-the-safety-of-your-own-home.html
50. U.S. Environmental Protection Agency. "Surface Coating of Automobiles and Light-Duty Trucks (NESHAP)"; "Small Entity Compliance Guide for Formaldehyde Standards — Fabricators (TSCA Title VI)"; "Clean School Bus Program." epa.gov. https://www.epa.gov/stationary-sources-air-pollution/surface-coating-automobiles-and-light-duty-trucks-national; https://www.epa.gov/sites/default/files/2018-04/documents/small_entity_compliance_for_formaldehyde_standards-fabricators_4.20.2018.pdf; https://www.epa.gov/cleanschoolbus