| 1 | KTTX | TTX Co. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 2 | KTTX | Trailer Train Co. | added 1/1964; 7/1965-1/1980; eliminated 1/1992 | | NAKINA |
| 3 | KTTX | Trailer Train Co. (FA flat cars equipped with tri-level automobile carrying superstructures with movable end sections of second, or second and third decks, furnished by member railroads. Cars are not equipped with hitches or bridge plates) | added 1/1964; 7/1965-10/1968 | | NAKINA |
| 4 | KTTX | Trailer Train Co. (flat cars, equipped with hinged end tri-level auto racks furnished by participant railroads) | 4/1970-1/1980 | | NAKINA |
| 5 | KTTX | Trailer Train Co./TTX Co. (standard deck flat cars with non-collapsable hitches, capable of handling any two trailers, with 36"" kingpin spacing, whose overall combined length does not exceed 90' — i.e., 2-45', 1-42' & 1-48', 1-40' & 1-48', etc. — between lift-on/lift-off facilities only) | 7/1985-7/2000 | | NAKINA |
| 6 | KTTX | Trailer Train Co. | Jul-65 | | NRHS |
| 7 | KTTX | Trailer Train Co. (FA flat cars equipped with tri-level automobile carrying superstructures with movable end sections of second, or second and third decks, furnished by member railroads. Cars are not equipped with hitches or bridge plates) | 10/66-10/68 | | NRHS |
| 8 | KTTX | Trailer Train Co. | Apr-70 | | NRHS |
| 9 | KTTX | Trailer Train Co. (flat cars, equipped with hinged end tri-level auto racks furnished by participant railroads) | 1/75-1/80 | | NRHS |
| 10 | KTTX | Trailer Train Co. | eliminated 1/92 | | NRHS |
| 11 | KTTX | TTX Co. | added 1/92 | | NRHS |
| 12 | KTTX | TTX Co. (standard deck flat cars with non-collapsable hitches, capable of handling any two trailers, with 36' kingpin spacing, whose overall combined length does not exceed 90' -- i.e., 2-45', 1-42' & 1-48', 1-40' & 1-48', etc. -- between lift on/lift off facilities only) | 1/94-7/2000 | | NRHS |
| 13 | KTTX | TTX COMPANY | | | PWRC |
| 14 | KTTX | Trailer Train (TTX Corporation) | | | RSRV |
| 15 | KTTX | TTX COMPANY | | | SCAC4 |
