Introduced in 1965, the 3000 horsepower GP-40 was the first 4 axle locomotive to use EMD's brand new 645 diesel engine.
The 272 GP-40's represented the largest group of second generation locomotive inherited by Conrail. All units came from the Penn Central, 154 units were purchased new by the PC, 103 were inherited by the NYC, the remaining 15 were purchased second hand from an EMD "loaner" fleet in 1969. These units were worked hard by the Penn Central and Conrail, powering the premier trains in the early dark days. Although they were all retired by 1991, many were brought out of retirement to handle the surge of traffic caused by the booming economy of the 1990's, the last units were finally retired for good in late 1995.