The M939 Truck is a 5-ton 66 U.S. military heavy truck. The basic cargo versions were designed to transport a 10,000 lb (4,500 kg) cargo load over all terrain in all weather. Designed in the late 1970s to replace the M39 and M809 series of trucks, it has been in service ever since. The M939 evolved into its own family of cargo trucks, prime movers, and recovery vehicles, with about 32,000 in all produced.

The M923 (M925 w/winch) had a body with drop sides so it could be loaded from the side by forklifts.