I don't recall any of the big 3 making such unit. Duallys were std cab long bed, ext cab long bed, and crew cab long bed. Short beds were single rear wheel. Cab and chassis units could also be had in std, ext, and crew cab with duals in the same wheelbases and Ford built std cab units on crewcab long wheelbase frames. They look strange when you see a welder/generator between the cab and the long utility bed.