| 1 | TTPX | Trailer Train Co. | 4/1970-1/1980; eliminated 1/1992 | | NAKINA |
| 2 | TTPX | TTX Co. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 3 | TTPX | Trailer Train Co./TTX Co. (flat cars equipped with bulkheads spaced 62' apart and 17 transverse tie-down anchors with chains; used for transporting wallboard, plywood, etc.) | 4/1970-1/1994 | | NAKINA |
| 4 | TTPX | TTX Co. (flat cars equipped with bulkheads spaced 62' apart and 17 transverse tie-down anchors with chains; used for transporting wallboard, plywood, etc., equipped with end of car cush.) | 7/2000 | | NAKINA |
| 5 | TTPX | Trailer Train Co. | Apr-70 | | NRHS |
| 6 | TTPX | Trailer Train Co. (flat cars equipped with bulkheads spaced 62' apart and 17 transverse tie-down anchors with chains; used for transporting wallboard, plywood, etc.) | 1/75-1/80; eliminated 1/92 | | NRHS |
| 7 | TTPX | TTX Co. (flat cars equipped with bulkheads spaced 62' apart and 17 transverse tie-down anchors with chains; used for transporting wallboard, plywood, etc.) | added 1/92; 1/94 | | NRHS |
| 8 | TTPX | TTX Co. (flat cars equipped with bulkheads spaced 62' apart and 17 transverse tie-down anchors with chains; used for transporting wallboard, plywood, etc., equipped with end of car cush.) | Jul-00 | | NRHS |
| 9 | TTPX | TTX COMPANY {TRAILER TRAIN COMPANY} | | | PWRC |
| 10 | TTPX | Trailer Train (TTX Corporation) | | | RSRV |
| 11 | TTPX | TTX COMPANY | | | SCAC4 |
