The FM H-20-44 was an multiple unit-capable end cab road switcher manufactured by Fairbanks-Morse from June 1947 – March 1954, and represented the company's first foray into the road switcher market. The 2,000 hp (1,490 kW), ten-cylinder opposed piston engine locomotive was referred to by F-M's engineering department as the "Heavy Duty" unit. It was configured in a B-B wheel arrangement mounted atop a pair of two-axle AAR Type-B road trucks with all axles powered.