The CCKW was very successful during WW2, amounting to almost a quarter of the total US truck production and ... the factory as general-purpose cargo models, GMC also built many specialized variants.

A GMC DUKW 353 military vehicle ... Commonly known as the Duck, the DUKW 353 was an amphibious version of the 2.5-ton, six-wheel-drive CCKW truck. It was used by the U.S. Army and U.S. Marine ...