A 1-1/2 ton might have a 2-speed rear, though I doubt that is common in a 4100 which has a 137 inch wheel base and the same frame basically as a 1-ton.

Good luck finding the right truck! You've sure got a bunch of opinions on just what it will be...

1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
It's true. I really don't do anything but browse the Internet looking for trouble...