| Company | City | WMI |
|---|
| X-L Specialized Trailers Inc. | Oelwein IA | 4U3 |
| X-Press | Storm Lake IA | 1X9-002 |
| X-Treme Trailer Manufacturing | Waxahachie TX | 5GV |
| Xtra Mile Trailers, Inc. | Gold Beach OR | 1X9-006 | |
| Xtreme Custom Conversions | Memphis TN | 1X9-009 |
| |
| Yale Steel, Inc. | Yale MI | 1Y9-006 |
| Yangzhou Tonghua Semi-Trailer Co. Ltd. | Yangzhou CN | LT1 |
| Yellowjacket Trailer Company | Blanchard OK | 1Y9-004 |
| Young's Welding, Inc. | Chanute KS | 5EP |
| Yukon Marine Corporation | Elkhart IN | 1Y9-008 |
| Yuma Welding & Fabrication | Yuma AZ | 1Y9-003 |
| |
| Z-1 Mini-Camp Trailer | Stockton CA | 1Z9-110 | |
| ZAT Enterprises | Comanche OK | 1Z9-116 |
| Zeligson Company | Tulsa OK | 1Z9-106 |
| Zephyr Trailer | Bixby OK | 1Z9-112 |
| Zerteck, Inc. d/b/a Warlock Trailer | Scotia NY | 1Z9-076 |
| Zieman Manufacturing Company | Phoenix AZ
San Bernardino CA
Whitter CA
Woodland CA | 1ZC
1RC
|
| Zierke Built Manufacturing | Winnebago MN | 1Z9-026 |
| Ziffel Manufacturing | Valley Springs CA | 1Z9-072 |
| Zimmer Motor Coach Corporation | Boca Raton FL | 1Z9-034 |
| Zimmerman Manufacturing Corporation | New Holland PA | 1Z9-108 |
| Zimmerman Metals Inc. | Denver CO | 1Z9-098 |
| Zona Industrial Campo Alegre | Cagua VE | 8X9-002 |
| |
| 1M Custom Car Transports, Inc. | Las Cruces NM | 119-001 | |
| 1st Choice Manufacturing, Inc. | Cambridge City IN | 16U |
| 33 East Maintenance, Inc. | Freehold NJ | 139-002 |
| 3T Equipment Company, Inc. | Santa Rosa CA | 139-001 |
| 4 Star Fabrication | Angola IN | 149-002 |
| 4-Star Trailers, Inc. | Oklahoma City OK
Oklahoma City OK | 1S9-113
4FK |
| 4x4 Trailers, Ltd. | Las Vegas NV | 149-004 |
| 5 Starr Trailer Company, Inc. | Langhorne PA | 1WE |
