I have searched the internet. I know mismatch front and rear axle ratios is not good. I know that there must be some sort of tolerance to this. I want to use a 3.73 rear with a 3.92 front. Cant find any 3.92 diffs in my area that will work. I do not want to pay for, or know how to, rebuild the present rear. I want to buy a used rear. The net says anywhere from 1% to 10% mix match is OK. Need to know what the Stovebolt community thinks/knows about this. I don't even know how to figure the per cent. Is it 3.92/3.73= 1.05% or is it 3.92-3.73=.19= 5%. ??? If I get a 3.73, I can get a 12 Bolt instead of the present 10 bolt. Truck is a 1960 GMC, 6 lug, 4x4 about 60" WMS-WMS. I believe it is a HO35 (old corporate 10 bolt).
Second question: I believe the HO35 is 55-62. I can find some 55-59 diffs. Most are 3.90/3.92, that's good...BUT why do they have a WWI helmet cover and mine has a ring gear bulge cover??? Did they just change the cover? Do I not have an HO35? Is it a GMC thing? I will check my diff cast numbers, The ring gear is dated 1960.
