| 1 | PDQX | Castle Capital Corp. | added 1/1971; 1/1975-1/1994; eliminated 1/1997; 7/2000-7/2005 (not listed) | | NAKINA |
| 2 | PDQX | Penn-Dixie Leasing Corp. | added 1/1969; 4/1970; eliminated 1/1971 | | NAKINA |
| 3 | PDQX | Callanan Equipment Corp. | added 10/1967; eliminated 1/1969 | | NAKINA |
| 4 | PDQX | Callanan Equipment Corp. | added 10/67; eliminated 1/69 | | NRHS |
| 5 | PDQX | Penn-Dixie Leasing Corp. | added 1/69; 4/70 | | NRHS |
| 6 | PDQX | Castle Capital Corp. | 1/75-1/94; eliminated 1/97; 7/2000 | | NRHS |
| 7 | PDQX | *PORT DEFIANCE, QUINALT & KLICKITAT RAILROAD | | | PWRC |
| 8 | PDQX | +CASTLE CAPITAL CORP. [PENN-DIXIE LEASING CORP.; CALLANAN EQUIPMENT CORP.] | | | PWRC |
| 9 | PDQX | Castle Capital Corporation | | | RSRV |
| 10 | PDQX | CASTLE CAPITAL CORP. | | | SCAC4 |
