Hi -

The original rearend should be an Eaton HO52. The Eaton HO52 and HO72 rearends were also used in 1967 through 1972 Chevy/GMC 3/4-ton trucks and are a direct swap/interchange. I picked up a 4.10 ratio carrier/rearend by shopping the classifieds at: www.67-72chevytrucks.com .

When I rebuilt my rearend on my '49 Chevy 3600, I found out that the bearing are barrel-shaped and seemed a bit pricey. However, overall, I like the stock appearance of the Eaton HO52 rearend.

Good Luck!
Dan M.