I don't think it's a 1/2 ton frame, unless it's from a flat top rail bed ('54-55.1) which had a much lower rear hump than a '47-5'2 1/2 ton. Also clues to it being a 3600 (3/4 ton) frame are the shock mounts mounted inboard of the rails. 1/2 ton would have shock mounts outside the frame rails. Also, a 1/2 ton frame has a fairly pronounced increase in width till just after the rearmost crossmember. A 3600 frame has parallel rails from just behind the cab which is what his pic looks like.
