The ALCO RSD-12 was a C-C diesel-electric locomotive rated at 1800 hp. 171 locomotives were produced —Used in much the same manner as its four-axle counterpart, the ALCO RS-11, though the six-motor design allowed better tractive effort at lower speeds.

Original buyers

Preservation

• Nickel Plate Road #329 is preserved at a museum in Bellevue, Ohio. • Southern Pacific #2954 and #2958 are preserved at the Southern California Railroad Museum in Perris, California. Both of these units are rebuilt from RSD-5s. • Paperton Junction Southern (ex-SP #2962) is preserved at the Arkansas Railroad Museum in Pine Bluff, Arkansas. • Lake Superior & Ishpeming #1804 partially survives in a shipyard in Escanaba, Michigan. It has no prime mover.