| RSD-4 (Specification E1663)|
The ALCO RSD-4 was a diesel-electric locomotive of the road switcher type rated at 1,600 horsepower (1.2 MW), that rode on three-axle trucks, having an C-C wheel arrangement.
Used in much the same manner as its four-axle counterpart, the ALCO RS-3, though the six-motor design allowed better tractive effort at lower speeds. Due to the inadequate capacity of the main generator, this model was later superseded in production by the ALCO RSD-5
ALCO RSD-4 Wikipedia
The only ALCO RSD-4 that has survived is Kennecott Copper Corporation #201. As of 2007, it resides in fully restored condition at the Northwest Railway Museum (formerly known as the Puget Sound & Snoqualmie Valley Railway) in Snoqualmie, Washington, wearing a coat of bright orange paint.