 Concurrently, EMD offered a six-axle (C-C) SD "(Special Duty)" locomotive, the SD7.The GP7 was replaced by the GP9 model in GM-EMD's GP sequence.ALCO, Fairbanks-Morse, and Baldwin had all introduced road switchers before EMD, whose first attempt at the road-switcher, the BL2 was unsuccessful in the market, selling only 58 units in the 14 months it was in production.