The Stovebolt Site Forums The Parking Lot Big Bolts GMC vs Chevrolet rear end?

I was driving around today and saw on old 51 (or so) GMC 300 flatbed with a two speed rear end. I noticed that it has a five lug rear end, rather than a ten lug rear end like my 49 Chevy. Also the hub diameter (where the wheel slides on) looked larger. Is there any advantage to this rear end, such as better (faster) gearing or late model wheel interchange that would let you run 22.5 inch rims? I was very surprised that GMC went to the trouble to have a different rear end, when the Chevy unit seem stout enough for most anything. Alright guys, I'm ready to get educated!
(If anyone is interested, the truck is in Tulsa, Ok and I could get a phone number)

Hy davesmith, Chevy trucks used Kelsey wheels [5 lug on the front, 10 lug on the rear]. GMC used Motor wheels in the early 50s, two things to remember GMC and Chevrolet are two different divisions of the same company, and that where Chevrolet truck production stopped, GMC went miles after that. Dayton wheels [heavy cast wheels with demountable rims] were also used by GMC during this period, but as far as I can remember they were never offered on Chevrolet trucks. As far as which is "better" thats a good question, but Dayton or Motor wheels are considered heavy duty compared to the Kelsey wheels used by Chevrolet. Some of the differentials are interchangeable between the heaviest Chevrolets, and some of the lighter GMCs. Brakes, hubs, axles, and axle housings are different between the two marques, and some would argue heavier on the GMC trucks, hope that helps.

GMC offered more options than Chevy in order to offer a truck tailored to the job. The one you saw is probably a heavier rear than your Chev. The ratio may well be slower than the Chev. The only way to tell is to examine it. And then of course, it could be a rear out of a completely different truck. It was common to go to a salvage yard and buy something that would fit.