The FM H-12-44TS was a light road switcher version of the Fairbanks-Morse H-12-44 yard switcher. Only three of the 1,200-horsepower (890 kW), six-cylinder opposed piston engine locomotives (builder numbers 12L1021–12L1023) were manufactured especially for the Atchison, Topeka and Santa Fe Railway in May, 1956.