This was the first model in EMD's SD(Special Duty) series of locomotives, a lengthened B-B GP7 with a C-C truck arrangement. The two extra axles and traction motors are useful in heavy, low-speed freight service. EMD continues to produce SD series locomotives to this day. Some SD7s both high and short-hood can still be found in service today on shortline railroads and industrial operators, although most Class I roads stopped using these locomotives by the 1970s and 1980s.[2][3]
^Pinkepank, Jerry A (1973). The Second Diesel Spotter's Guide. Kalmbach Books. p. 71. LCCN66-22894.