Introduced in January, 1966, EMD’s GP38 was the last fully new model in the “GP” line to lack a turbocharger. These locomotives were powered by a Roots Blower equipped, 16 cylinder 645 engine and rated at 2,000 horsepower. They were designed as a medium horsepower locomotive, intended to replace older diesel models and without the increased costs of high horsepower turbocharged engines. As such, they continued in the fashion of the earlier F-Units as well as the early 567 engined GP7, GP9, GP18 and GP28 models.