The 2+1⁄2-ton, 6×6 truck was a standard class of medium duty trucks, designed at the beginning of World War II for the US Armed Forces, in service for over half a century, from 1940 into the 1990s. Also frequently known as the deuce and a half, or just deuce, this nickname was popularized post WWII, most likely in the Vietnam war era. The basic cargo versions were designed to transport a cargo load of nominally 2+1⁄2 short tons over all terrain, in all weather. The 2+1⁄2-ton trucks were used ubiquitously in World War II, and continued to be the U.S. standard medium duty truck class after the war, including wide usage in the Korean and Vietnam Wars, as well as the first Gulf War.

The GMC CCKW, also known as "Jimmy", or the G-508 by its Ordnance Supply Catalog number, was a highly successful series of off-road capable, 21⁄2-ton, 6×6 trucks, built in large numbers to a standardized design for the U.S. Army, that saw heavy service, predominantly as cargo trucks, in both World War II and the Korean War. The original "Deuce and a Half", it formed the backbone of the famed Red Ball Express that kept Allied armies supplied as they pushed eastward after the Normandy invasion.