Unlike the original GP39, which sold only 23 examples as railroads preferred the reliable un-turbocharged GP38, the GP39-2 was reasonably successful, ascribed to its better fuel economy relative to the GP38-2 which became of more interest in the 1970s energy crisis, and to its better performance at altitude.[1]
Original owners
The GP39-2 sold to five railroads and two industrial operators:[2]
705-711 and 779-799 were built with raised cab roofs and extra windows for improved visibility in the Bingham open pit copper mine. Kennecott #3 was built for the Ray Mines Division of Kennecott Copper Corporation
Union Pacific has rebuilt 7 of their GP39-2's into GP39N's at their Jenk's shop. These units received a microprocessor control system to increase adhesion, control options, and extend the life of the locomotive.[3][4]