Chevrolet and GMC did offer 1 ton 4x4s, however '59 was the last year for them until '79. Strangely enough, though, they did offer 1 1/2 ton and 2 ton 4x4s in the mid '60s. It was an aftermarket produced/factory installed option manufactred by the American Coleman company, who also made similar conversions for Ford, IH (both truck and tractor), and Mack. They also produced conversions for most of the tractor manufacturers well into the '80s.
