Original Rear End or......?

[JWheeler331]

I was looking over the FAQ section and seen some good stuff on rear ends but that got me wondering. Just what do I have.

I assume its the original since the truck is still Drum/Drum 6 lugs.

If it is original does anyone know the gearing that would have came in it?

Are they good or should I look for a 12 bolt posi?

Are there any of the later Chevy Rear ends that would mount straight up to what I have that are 6 lug?

If this has been covered and there is a link with a simple answer im sorry. Sometimes I over read or over think things.







I would love to change to rear disk brakes sometime in the near future and would love to just find something that would bolt straight up to my frame.

Part of my Early Classic front disk brake swap parts came in today.

[Greg63]

That is the stock original rear axle.
It either had 3.73:1 or 4.11:1 ratio.
Greg.

[JWheeler331]

Originally Posted by Greg63

That is the stock original rear axle.
It either had 3.73:1 or 4.11:1 ratio.
Greg.

Thanks.

Does the rear end have a name or call number? Its on a 1/2 ton short step.

[Greg63]

12 bolt truck differential. 1963 - 1972(?)
Greg.

[66Submarine]

1963-1982. Often quoted as 64-82, though.

[JWheeler331]

Originally Posted by 66Submarine

1963-1982. Often quoted as 64-82, though.

That is what can replace the original?
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[jayoldschool]

Originally Posted by Greg63

That is the stock original rear axle.
It either had 3.73:1 or 4.11:1 ratio.
Greg.

I believe 3.73 was the stock ratio, with 4.11 and 3.07 optional.

[66Submarine]

Not as a direct swap, that was just the run for the 12 bolt truck rear. 65-70 (maybe late 64 too?) is a direct swap with 6 lugs and coil springs. 63-64 had a fabricated panhard bar mount on the axle tube, 71-72 were five lug, and 73 up had leaf springs. The differential carrier itself interchanges with all of them, although early trucks had coarse spline axles. (63 and 64 I think)

[WhippinSaw]

There is a stamping on the axle on the other side by the vent and fill plug. Mine was a GM5 which is the 3.73 ratio. I had to clean it before I could find it.

[JWheeler331]

Originally Posted by WhippinSaw

There is a stamping on the axle on the other side by the vent and fill plug. Mine was a GM5 which is the 3.73 ratio. I had to clean it before I could find it.

Thanks, I will check it out tomorrow when im over there.