The Diamond T 980 12-ton Prime Mover (Later designated M20 by the U.S. Army), was originally designed to meet a British requirement for a vehicle capable of recovering and transporting tanks. The design and testing was completed in 1940, and production commenced in 1941. The Diamond T 980 first saw action with the British Eighth Army in North Africa. The 980 featured a heavy ballast body behind the cab and a 20-ton winch with a 300-foot cable. Later, a 981 version was introduced to meet U.S. requirements as well. It featured a 500-foot winch cable with winch-cable roller sheaves added to the front (the 980 only had winch-cable roller sheaves at the back). The front cable rollers gave the 981 self-recovery capability. Starting in August 1943, the 981s were fitted with a wider three-seat open cab (as displayed) with provision for the M36 anti-aircraft, .50 caliber machine gun ring-mount. The Diamond T 981 in this new configuration was designated the M20. The M9 trailer was capable of transporting the 38-ton British “Churchill tank” (their heaviest tank) as well as the U.S. built, 32-ton “Sherman” tank. A total of 5,871 Diamond T 980/981/M20s were manufactured during World War II.