EMD introduced the SW1200 in 1954 as the successor to the SW900. Between 1959 and 1963, EMD began rebuilding the Reading Company's aging fleet of Baldwin VO1000's into these new improved switchers. EMD reused the following parts of the VO1000's on the new locomotives: main generator, auxiliary generator, batteries, trucks, frame, cab, horn, and bell. The Reading Company classed these rebuilds as VO1000M's. When Conrail inherited the twenty rebuilt switchers, they reclassified them as SW1200M's.

Comprehensive EMD SW1200M Roster

The roster below is comprehensive for Conrail's SW1200M switchers between their inclusion in Conrail in 1976 and contains all twenty SW1200M switchers that Conrail inherited. Currently, the roster does not contain retirement dates and dispositions due to their complex nature. Of course, all the SW1200M's were retired long before June 1999.

CR     Former     Reblt   Prior    Built
========================================
9301   RDG 2701   05/59   RDG 81   08/40 
9302   RDG 2702   05/59   RDG 80   08/40 
9303   RDG 2703   04/59   RDG 74   11/43 
9304   RDG 2704   04/59   RDG 73   06/43 
9305   RDG 2705   03/59   RDG 75   11/43 
9306   RDG 2706   02/59   RDG 55   08/44 
9307   RDG 2707   03/59   RDG 78   01/44 
9308   RDG 2708   03/59   RDG 56   08/44 
9309   RDG 2709   04/59   RDG 59   09/44 
9310   RDG 2710   04/59   RDG 58   09/44 
9311   RDG 2711   04/59   RDG 57   08/44 
9312   RDG 2712   04/59   RDG 71   06/43 
9313   RDG 2713   04/59   RDG 88   03/44 
9314   RDG 2714   03/59   RDG 89   01/44 
9315   RDG 2715   11/63   RDG 77   01/49 
9316   RDG 2716   11/63   RDG 79   01/44 
9317   RDG 2717   11/63   RDG 87   03/44 
9318   RDG 2718   11/63   RDG 85   06/43 
9319   RDG 2719   11/63   RDG 72   06/43