EMD's engineering department pushed their DC traction system for an extra . The wasn't quite equivalent to the GE and ALCO offerings, but EMD hoped the railroads' familiarity with EMD equipment would improve their chances. The locomotive in which the 16 cylinder, 567D3 would be fitted, was improved along the lines of the U25B; sealed long hood, central air intake, and engineered for easier maintenance access. The frame and trucks of the GP20 were carried across; the extra equipment for the centralized air system required more space behind the cab, and since the locomotive was not going to be lengthened, extra space was achieved vertically by raising the height of the locomotive, giving room for the central air system, turbocharger and electrical cabinet all behind the cab. This extra height behind the cab meant that the body style used for previous GP units was not suitable.