| 1 | TTBX | Trailer Train Co. | added 4/1968; 10/1968-1/1980; eliminated 1/1992 | | NAKINA |
| 2 | TTBX | TTX Co. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 3 | TTBX | Trailer Train Co. | added 4/1968 | | NAKINA |
| 4 | TTBX | Trailer Train Co. (89'3"" and over FA flats equipped with bi-level automobile carrying superstructures furnished by member railroads. Cars are not equipped with hitches and bridge plates. Equipped with hydraulic draft gear) | 10/1968 | | NAKINA |
| 5 | TTBX | Trailer Train Co. (flat cars, length 89'4"" or over, equipped with bi-level auto racks furnished by member railroads) | 4/1970 | | NAKINA |
| 6 | TTBX | Trailer Train Co./TTX Co. (flat cars equipped with bi-level auto racks furnished by participant railroads) | 1/1975-7/2000 | | NAKINA |
| 7 | TTBX | Trailer Train Co. | added 4/68 | | NRHS |
| 8 | TTBX | Trailer Train Co. (89'3" and over FA flats equipped with bi-level automobile carrying superstructures furnished by member railroads. Cars are not equipped with hitches and bridge plates. Equipped with hydraulic draft gear) | Oct-68 | | NRHS |
| 9 | TTBX | Trailer Train Co. | Apr-70 | | NRHS |
| 10 | TTBX | Trailer Train Co. (flat cars equipped with bi-level auto racks furnished by participant railroads) | 1/75-1/80; eliminated 1/92 | | NRHS |
| 11 | TTBX | TTX Co. (flat cars equipped with bi-level auto racks furnished by participant railroads) | added 1/92; 1/94-7/2000 | | NRHS |
| 12 | TTBX | TTX COMPANY {TRAILER TRAIN COMPANY} | | | PWRC |
| 13 | TTBX | Trailer Train (TTX Corporation) | | | RSRV |
| 14 | TTBX | TTX COMPANY | | | SCAC4 |
