| 1 | XTTI | X-TREME TRANSPORT INC | | | SCAC4 |
| 2 | XTTX | Trailer Train Co. | added 4/1966 | | NAKINA |
| 3 | XTTX | Trailer Train Co. (FC flat cars equipped with hitches and bridge plates for the transportation of trailers. These cars have 4 hitches for handling 2 40-foot or 3 28-foot trailers) | 10/1966-10/1968 | | NAKINA |
| 4 | XTTX | Trailer Train Co. (flat cars, equipped with 4 hitches and bridge plates for the transportation of two trailers, 1 45' and 1 40' or 3 28' trailers) | 4/1970-7/1985 | | NAKINA |
| 5 | XTTX | TTX Co. (flat cars equipped with 4 collapsable hitches and bridge plates for the transportation of two trailers, 1-45' and 1-40' or 3-28' trailers) | 1/1992 | | NAKINA |
| 6 | XTTX | TTX Co. | 1/1994 | | NAKINA |
| 7 | XTTX | Trailer Train Co. | added 4/1966; 1/1975-1/1980; eliminated 1/1992 | | NAKINA |
| 8 | XTTX | TTX Co. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 9 | XTTX | Trailer Train Co. | added 4/66 | | NRHS |
| 10 | XTTX | Trailer Train Co. (flat cars, equipped with 4 hitches and bridge plates for the transportation of two trailers, 1 45' and 1 40' or 3 28' trailers) | 1/75-1/80 | | NRHS |
| 11 | XTTX | Trailer Train Co. | eliminated 1/92 | | NRHS |
| 12 | XTTX | TTX Co. | added 1/92 | | NRHS |
| 13 | XTTX | Trailer Train Co. (FC flat cars equipped with hitches and bridge plates for the transportation of trailers. These cars have 4 hitches for handling 2 40-foot or 3 28-foot trailers) | 10/66-10/68 | | NRHS |
| 14 | XTTX | Trailer Train Co. | Apr-70 | | NRHS |
| 15 | XTTX | TTX Co. | Jan-94 | | NRHS |
| 16 | XTTX | TTX COMPANY (TRAILER TRAIN COMPANY) | | | PWRC |
| 17 | XTTX | Trailer Train (TTX Corporation) | | | RSRV |
| 18 | XTTX | TTX COMPANY | | | SCAC4 |
