The Alco RSD-15's were built between 1956 and 1960 in Schenectady, New York. The RSD-15 was powered by an Alco 251 16-cylinder V-type engine. Rated at 2,400 horsepower, these versatile locomotives were suited for mainline freight and passenger service. The locomotive rode on 3-axle trucks with all axles powered by GE model 752 traction motors. The trucks have asymmetrical axle spacing because of the position of the traction motors. The six-motor design allowed for higher tractive effort at lower speeds than a similar four-motor design.
The RSD-15's could be ordered with either a high or low short hood, and the low hood versions quickly earned the nickname "alligators" due to their unusually long noses.