The 3/4-ton dually had different wheels than the 1-ton, or at least the one I looked at did, but I'm pretty sure it was dually hubs in the front. The cab serial number will tell what it is.
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...
