8 bolt rearend

[67 Builder]

I have a 10 bolt, how do i tell what size it is and does it matter. i am gonna have it rebuilt into a 8.5 is this poosible if it was a 8.25 to begin with? thanks robb

[chicane67]

You meant to say that you have 10 bolt 8.2 rear end ?? Ok...

I have put 8.5" posi's into the 8.2" housing... but it was more of a "I told you I could do it" thing. So in other words an 8.2" is an 8.2". If you want an 8.5", you'll have to purchase one... but an 8.2" cannot really be made into an 8.5" for lack of a better explaination.

Now, how do you tell them apart. Well, without pictures I will tell you that the 8.2" rear cover has an 'eyebrow' across the cover and the 8.5" does not... its smooth across it. There are 10 bolts on both and in the same position/locations. The internal parts however, will tell you everything... but that would require you to remove the rear cover.

Hopefully, Big Gear Head will pull out the photos to show the visual differences...

Yo Freddy !! (insert big red punch bowl crashing through a wall with a photo album here)

[67 Builder]

I have a 10 bolt housing with axles and nothing else., bare. So your saying I can make it into what ever? The internal make it. Housings are the same? Thanks robb

[big gear head]

If you want an 8.5 you need to start with an 8.5. You will get into some problems trying to cross parts. A rear end is difficult to assemble when the right parts are used, and very difficult when you start mixing parts.

As for idintification, the 8.2 has a 1 1/8 pinion nut and 3/8 ring gear bolts with 9/16 heads. The 8.5 has a 1 1/4 pinion nut and 7/16 ring gear bolts with 3/4 heads and left hand threads. Both have 28 spline axles and the 8.2 has a 25 spline pinion shaft and the 8.5 has a 30 spline pinion shaft.

[67 Builder]

Thanks for the info. All i have is the housing. and I want to put everything new 8.5 inside. But I dont know what the housing is? You said I can tell buy the cover and the bolt sizes and pinion size but i dont have any of that. Will this work? Sorry I didn't clairify very well. Thanks for the replys

[big gear head]

The only way that you will be able to tell is by the casting. You could go by the date because no 8.2 rear ends were made after '71. The 8.5 has 2 square corners at the bottom of the casting where the cover bolts on and the 8.2 has 2 half circle cut outs in the same location.

[67 Builder]

Thanks Gear head!!

[MonzaRacer]

Well it also depends on the version of 8,2 diff you have but luckily the 8.2 pontiac and the 8,2 chevy center and gears are interchangeable.
I bought a set of 4.88s for my 70 Monte a long time ago and it had a set of 8.2 chevy gears with a cone type posi from a 69 RamAir TA that was turned into a drag car. The guy I bought it off of made spacer sleeves as the Pontiac center has larger bolts than the chevy gears (chevy gears have small bolts).
He banged a 4 gear with a VERY stout 400 with Carne superflow RA4 heads, race preped and it held and I drove it on the street for 7 or 8 months till I got ran off road and siddeswiped a telephone pole and bent an axle so back in went the old first gen Abody 12 bolt 355 posi(narrower axle was easier to put Corvette ralleys on anyway).
Good luck
Lee