I'm looking on E-bay for a posi unit. There is several listed, some say for certain years, like 1989 for example. Are there any differance between the 8.5 rearend from a Camaro and Nova compaired to the later rearends? I don't want to buy something that will not fit.

89 wont work...not an 8.5, and has coil perches...set up for the factory 4 link...what yr are you looking to put it in???

You need ta hunt up the Nova site link that has a bunch of rearend ID info on it.

pdq67

1st question... Are you sure, you have an 8.5 rear ? First Gen. Camaros had the 8.2 rear, the Nova's had 8.5's. 2nd Gen. Camaro's had the 8.5. All of these were 10 bolts !

3rd and 4th gen Camaros & Firebirds (82 and up) have a 7.5" carrier in their 10 bolt rearend so their guts won't interchange. As well they are coil spring suspension.

As has been stated, 8.2" parts will not interchange with an 8.5" even though all are 10 bolt rear ends.

BUT, certain year 8.5" 10 bolts (X-car clones) have the same spring perch dimensions as 1st gen Camaro 8.2" 10 bolts and because of this are a stronger bolt in replacement.

Confused yet?

if the OP was just asking about the differential unit- the "posi" unit- then the later truck stuff will bolt right in..

but..

you will need to upgrade to 30 spline axles in place of your stock 28 spline axles- i wonder if 12 bolt axles are the right length?- and in the end, you would have either a crappy worn out cone style posi or weak a locking differential, depending on what year car or truck it came out of.
the best bet for a good posi unit for an 8.5 is mid to late 70's Z/28's ant Trans Ams, Chevelles, Monte Carlos, and Novas, as they have the Eaton posi unit. you are most likely to find a posi under a Z or TA, but they are more likely to have highway gears and the associated 3 series carrier that no one makes gearsets in a decent ratio for. of course, there are spacers to put deep gears on these units, but now i'm just starting to ramble..

Thanks for the replys. I have bought a 10 bolt 8.5 rear end, but it's an open carrier that will bolt in my car. I want to find a posi carrier to put in it. I'm looking on E-Bay, trying not to spend 500.00 on a new one.

Here is what I am looking at:

http://cgi.ebay.com/ebaymotors/GM-8-5-10-Bolt-Auburn-30-Spline-Posi-Unit-Impala-ss_W0QQcmdZViewItemQQcategoryZ33731QQihZ008QQitemZ 180199216588QQrdZ1QQsspagenameZWDVW

Lukeskywalker, I am trying to do the same thing. I just scored that same Posi at PickNPull. Your current rearend is probably a 28 spline axle so new axles will be in order or look for a 28 spline posi unit like Novaderrick sugested. I was just adding mine up and it comes out like this.
1. 10 bolt rear = 125.00 at junkyard
2. posi carrier = 50.00 at junkyard
3. 30 spline Moser axles = 230.00
4. New gears = 170.00
5. Mega install kit =170.00
total = 745.00 or so plus any install costs
Supposedly, the 8.5 with 30 spline axles is as strong as the 12 bolt at about half the cost but the cool factor is lost with it.

Great idea for the Pick and Pull. What did you get your posi out of?

93 Buick Roadmaster. I thought about taking the whole rearend but it's 62 inches wide and has link ears on the top. Some of the newer 1/2 ton trucks have the Auburn type posi with 3:73 gears but some have the Gov-Loc which is no good. I wish member "Big Gear Head" was still around, he knew everything about this subject. P.S. PickNPull is is having a 1/2 price sale till the 1st I believe. The carrier was 24.00 but they add on a core charge,enviromental fee, tax and it came to about 40.00 I typed in 10 bolt posi on Ebay and it gave a listing that had a list of the cars and trucks from 89-98 that it came in. Your local PicknPull probably has a Interchange that could tell you also.

As X44 stated BGH knew everything on the subject. But I think by the many posts that I have read of his and PM's that he has sent me on the subject. He would say to use an Eaton posi unit. Just got done installing a 12 bolt posi rear in my 69 with Eaton 3.55. Know for the snow to melt. Now no more embarassing burnouts.