| 1 | TTNX | Texas Tanning Extract Co. | 4/1947-1/1952 | | NAKINA |
| 2 | TTNX | Trailer Train Co. | added 5/1983; eliminated 1/1992 | | NAKINA |
| 3 | TTNX | TTX Co. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 4 | TTNX | Trailer Train Co. (flat cars equipped with bi-level auto racks without end doors and with or without roof panels) | added 5/1983; 7/1985 | | NAKINA |
| 5 | TTNX | Trailer Train Co. (not defined) | 10/1991 | | NAKINA |
| 6 | TTNX | TTX Co. (flat car equipped with fully enclosed unilevel rack furnished by participants. Used for loading large trucks) | 1/1992-1/1994 | | NAKINA |
| 7 | TTNX | Texas Tanning Extract Co. | Jan-52 | | NRHS |
| 8 | TTNX | Trailer Train Co. | added 5/83; eliminated 1/92 | | NRHS |
| 9 | TTNX | TTX Co. | added 1/92; 1/94 | | NRHS |
| 10 | TTNX | *TEXAS TANNING EXTRACT CO. | | | PWRC |
| 11 | TTNX | +TTX COMPANY {TRAILER TRAIN COMPANY} | | | PWRC |
| 12 | TTNX | Trailer Train (TTX Corporation) | | | RSRV |
| 13 | TTNX | TTX COMPANY | | | SCAC4 |
