GP15-1 The GP15-1 was the most popular variant as it did not contain either of the newer technologies of the other two variants (turbocharging or AC control). EMD built a total of 310 units for
American railroads in this variant between June 1976 and March 1982. The
Missouri Pacific Railroad purchased more units than the other three buyers combined. For spotting purposes, the MP models have a number of visually distinguishing features, though not all were applied consistently to the MP units: • The MP units have a grab iron ladder mounted on both sides of the long hood end; • MP's initial order of GP15-1s rode on
Blomberg M trucks rather than the more common
Blomberg B (all subsequent units were delivered with Blomberg B trucks) — and, while the standard Blomberg B truck carries two brake shoes per wheel, many MP units were equipped with only a single brake shoe per wheel; • #1555–#1574 were outfitted with the standard 81" nose, while the remaining units (all built in December 1976 or later) came with an 88" nose;
GP15T EMD built 28 examples of a variant, the
GP15T, between October 1982 and April 1983. It was a very close cousin to the GP15-1, but used a turbocharger in order to generate more power from a smaller engine. Power was provided by an 8-
cylinder diesel engine that generated , the same as the GP15-1, but with four fewer cylinders. 28 examples of this locomotive model were built for
American railroads. The
Chessie System received the majority of them as C&O 1500–1524 (25 units), while the rest went to the
Apalachicola Northern Railroad in Florida as AN 720–722 (3 units). Chessie System's units were the only GP15s to be built with
dynamic brakes.
GP15AC The
GP15AC is a variant built between November and December 1982. This model differs from the GP15-1 due to Missouri Pacific specifying new AR10 AC alternators instead of rebuilt D32 DC generators. The only external difference between the GP15AC and the GP15-1 is a straight side sill (shared with the
EMD GP15T) not related to the transmission difference. 34 examples of this locomotive model were built in total: 30 for
Missouri Pacific Railroad, and four for Venezuela's
IFE. == Rebuilds ==