64 C10 12 Bolt Rear Axle

[gsharp]

Couple things, I want to convert the rear axle on my 64 to 5 lug and put a 3.08:1 ring and pinion in. Question is the 64 12 bolt not the same as the up to 72 rear ends? What size carrier is in my 64 12 bolt with the factory 3.73:1 gears?

[gmc684x4]

The carrier will be the same
The axles are the same up to early 70
Late 70 to about 81 the 12 bolt is slightly wider taking a different axle set
Summit Moser and many others have 5 bolt axles for the pre 70 12 bolt

[cwcarpenter98]

The 63-64 12 bolts used 17 spline axles and spider gears. I've read that the axle bearing is different as well, but can't confirm myself as the previous owner swapped in a 65-70 12 bolt a long time ago

[The Rocknrod]

I bought an entire kit hub to hub from Quick for my 64 12 bolt. Moser 31 spline, Detroit gears, Eaton posi, bearings seals etc.
However the seals were different than what came with the kit, the ones I needed were National Oil Seals 8871.

[gmc684x4]

I thought they where all the same spline
all my diffs are 67 to 77 I have in my collection
early 12 bolt truck axles are 30 3/4 " long
late 70 up are 31 7/16 " long

you can contact Usa standard Gear ask about the axle bearings difference use a newer 30 spline carrier posi or open in a 3 series

or look for a newer diff with 3.08 in it already

this is the 5 bolt swap axles from rock auto for a 67 diff

https://www.rockauto.com/en/moreinfo...321108&jsn=984