The EMD GP38 is a four-axle diesel-electric locomotive built by General Motors Electro-Motive Division between January 1966 and December 1971. The locomotive's prime mover was an EMD 645 16-cylinder engine that generated 2,000 horsepower (1.49 MW). The company built 706 GP38s for North American railroads.

The EMD 645 is a family of diesel engines that was designed and manufactured by the Electro-Motive Division of General Motors. While the 645 series was intended primarily for locomotive, marine and stationary engine use, one 16-cylinder version powered the 33-19 "Titan" prototype haul truck designed by GM's Terex division