The N scale locomotive is modeled after Electro Motive Division's 2000 horsepower GP-38 diesel introduced in the late 1960's and early 1970's and is still in service today throughout North America. The GP-40 was the 3000 horsepower successor to the GP-38, best characterized by the three full size radiator fans on the rear of the roof. The GP40-2 had mostly internal changes but several outside details such as bolted down battery box covers and a roof that extended slightly beyond the rear of the cab differed it visually from the GP-40.