The Diamond T 4-ton 6×6 truck was a heavy tactical truck built for the United States Army during World War II. Its G-number was G-509. Cargo models were designed to transport a 4-ton (3,600 kg) load over all terrain in all weather. There were also wrecker, dump, and other models. They were replaced by the M39 series 5-ton 6×6 trucks in the 1950s.