2½-ton 6×6 truck

During World War II the most important model for the U.S. Army was the GMC CCKW or "Jimmy", with over 560,000 units built.

First fielded in the 1950s, the M35 family became one of the most successful and long-lived series of trucks ever deployed by the U.S. military.

The 2+1⁄2-ton cargo truck was considered such a valuable piece of equipment that General Eisenhower wrote that most senior officers regarded it as "one of the six most vital" U.S. vehicles to win the war.

[nb 3] It has been called the most important truck of World War II, and the 6×6 became known as the "workhorse of the army".

[1] According to Hyde (2013): "Each of the three axles had its own differential, so power could be applied to all six wheels on rough terrain and steep hills.

The front axle was typically disengaged on smooth highways, where these 'workhorses' often carried loads much above their rated capacity.

[3] In 1939-1940 the U.S. Army Ordnance Corps was developing a 2+1⁄2-ton (5,000 lbs, 2,300 kg) load-rated 6×6 tactical cargo truck that could operate off-road in all weather.

[10][11] As the standard US Army design during World War II, over 560,000 were built, more than any other US vehicle except the "Jeep".

AFKWX, 6x4 CCW, and amphibious DUKW were mechanically virtually identical and were built next to CCKWs in both plants.

The Studebakers were very successful in the Soviet Union, where they carried large loads on poor roads in extreme weather.

After the war, the basic design of the Studebaker US6 was closely copied in the Soviet Union to develop the GAZ-51 and GAZ-63 trucks, which were produced between 1946 and 1975.

500 M-5-6s and 3,000 M-5-6x4s, with a commercial International K truck model cab, were complete by 1942, and were exported to the Soviet Union.

The design then was upgraded, with a larger engine, tires, military open cab, and other improvements, and standardized as the M-5H-6 for the US Navy and Marines.

[22][23][24][25][26] The standard post-war 2+1⁄2-ton truck M35 was manufactured by REO, Kaiser-Jeep, Curtis-Wright, Studebaker, Studebaker-Packard, AM General, and Bombardier (Canada) from 1950 until the late 1980s, with remanufacture extending into FY1999.

[27][28][29] An evolution from their widely successful CCKW, General Motors' successor "Deuce and a Half" 2+1⁄2-ton M135 was classed as a substitute standard in the US Army after the REO M35 was standardized, and thus was employed in much smaller numbers, but the M135 was also widely used by the Canadian Army.

In 1942, to simplify production and reduce shipping height, all manufacturers began to use military style open cabs.

GMC made a few tractors based on the CCKW 352[44] during World War II.

Most World War II units could be fitted with bows and a tarpaulin to camouflage themselves as common cargo trucks.

Maintenance, engineer, water purification, pole-setting, air compressors, fire fighting, and other equipment were also mounted on chassis cabs.