I know that the 1 Ton frame extends further forward then the 1/2 Ton. The bumper supports on the 1/2 Ton curve out from the frame whereas the 1 Ton has bumper attachments on the front of the frame that attach to the bumper support which is a cross bar.

1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

My Chevy Master 4 Door is on the Road!