| 1 | SPSX | Stickney & Poor Spice Co. | 1/1946 (not listed); 4/1947-7/1954; eliminated 1/1955 | | NAKINA |
| 2 | SPSX | Steel Processing Services, Inc. | added 1/1990; eliminated 10/1993 | | NAKINA |
| 3 | SPSX | Progress Rail Services Corp. | added 10/1993; 1/1994-7/2005 | | NAKINA |
| 4 | SPSX | Stickney & Poor Spice Co. | Jan-52 | | NRHS |
| 5 | SPSX | Steel Processing Services, Inc. | added 1/90; eliminated 10/93 | | NRHS |
| 6 | SPSX | Progress Rail Services Corp. | added 10/93; 1/94-7/2000 | | NRHS |
| 7 | SPSX | *STICKNEY & POOR SPICE CO. | | | PWRC |
| 8 | SPSX | +PROGRESS RAIL SERVICES CORPORATION {STEEL PROCESSING SERVICES, INC.] | | | PWRC |
| 9 | SPSX | Progress Rail Services Corporation | | | RSRV |