The pictures on Rock Auto of the GMT 400 type 1-ton four wheel drive rotors suggest the opening will be 4.6+. It's not a round hole or bore as such, but the opening comes close to the holes for the lugs.
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...