It was actually a 3600 truck with a 70's 1/2 ton front clip. The rear of the frame had been shortened too, for a shortbed. I guess you can say it was a 49 3/4 ton turned 1/2 ton with a 70's front clip. (Boy, that's a mouthful.) I didn't climb underneath to see where it was spliced, but with the hood open , it was pretty clean.