| 1 | TTGX | Trailer Train Co. | 4/1970-1/1975; added 1/1977; 1/1980; eliminated 1/1992 | | NAKINA |
| 2 | TTGX | TTX Co. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 3 | TTGX | Trailer Train Co. | 4/1970 | | NAKINA |
| 4 | TTGX | Trailer Train Co. (no definition) | 1/1975 | | NAKINA |
| 5 | TTGX | Trailer Train Co. | 4/1970; added 1/1977 | | NAKINA |
| 6 | TTGX | Trailer Train Co./TTX Co. (flat cars equipped with fully enclosed bi-level auto racks furnished by participant railroads) | 1/1980-1/1994 | | NAKINA |
| 7 | TTGX | TTX Co. (flat cars equipped with fully enclosed bi-level auto racks furnished by participant railroads, equipped with end of car cush.) | 7/2000 | | NAKINA |
| 8 | TTGX | Trailer Train Co. | Apr-70 | | NRHS |
| 9 | TTGX | Trailer Train Co. (no definition) | Jan-75 | | NRHS |
| 10 | TTGX | Trailer Train Co. | 4/70; added 1/77 | | NRHS |
| 11 | TTGX | Trailer Train Co. (flat cars equipped with fully enclosed bi-level auto racks furnished by participant railroads) | 1/80; eliminated 1/92 | | NRHS |
| 12 | TTGX | TTX Co. (flat cars equipped with fully enclosed bi-level auto racks furnished by participant railroads) | added 1/92; 1/94 | | NRHS |
| 13 | TTGX | TTX Co. (flat cars equipped with fully enclosed bi-level auto racks furnished by participant railroads, equipped with end of car cush.) | Jul-00 | | NRHS |
| 14 | TTGX | TTX COMPANY {TRAILER TRAIN COMPANY} | | | PWRC |
| 15 | TTGX | Trailer Train (TTX Corporation) | | | RSRV |
| 16 | TTGX | TTX COMPANY | | | SCAC4 |
