I bought this because I was told it was an auburn 10 bolt 7.5 posi for 28 spline axles, but after running the #'s off of it I've been unable to match it to anything. The #'s i've found are # 71189 and a # that has been etched in by hand reads 8J97-59A. In the first pick there's a casting mark right below the bearing that looks like a P inside a D. The mark down and to the right from that one is a C or G. Thanks.

 

None of my Auburns ever had that blocky thing in the access window.

 

Yeah,I can't visually match it to anything in the auburn product line.

 

After hours of browsing summit it looks like it's a Detroit locker but I still can't get a hit on the part numbers. Any way to tell if it's a 7.5 28 spline posi? Take a look at the link and let me know if it looks like a match to you.

http://www.summitracing.com/parts/DTL-162C59A/

http://www.summitracing.com/parts/DTL-162C58A/?rtype=10

 

Looks like it.
Start counting axle splines inside.

 

Okay, so i counted the splines 3 times just to be sure and I came up with 28. So far I believe I have a 10 bolt 28 spline Detroit locker. I still don't know if it's for a 7.5 and i have no idea how to determine that. Anyone know how? Thanks for the help so far!

 

Start up a chat or phone call Summit and ask for the o.d. where the ring seats.

There are only so many 28 spline apps out there.

 

I called Eaton and they confirmed that it's a 7.5 10 bolt 28 spline Detroit locker for Gm 3.23 and up. I'm pretty excited seeing as I only paid $190 for it, a 87-94 4 bolt main roller shortblock, and a 400 crank. Now I have a new question. I want to put this in my 89 Iroc which was equipped with a 305 TPI and a 700R4. I'm pretty sure it has an open rear with a 2.73 gear in it. I know I need a set of Moser 28 spline axles and i'm swapping to a 3.73, but what else do I need for this swap? Thanks.

 

I think there was an adapter to use a 2pc seal crank in a 1pc seal block since any 400 is a 2pc rear main seal.

New flexplate; 153 tooth let you keep the same starter.

 

No, I meant what else do I need for the rear end swap?

 

When you order the ring and pinion for the 3:73 gears you will also need to order an installation kit for the bearings, shims, crush sleeve, etc.
I believe with the axles you will need new axle bearings and seals. Even if you do not need them I would put new in anyways while doing that much work.
What are you doing for rear brakes? Is your current diff a 9 or a 10 bolt? If it is a 9 bolt then that carrier will not fit. I am assuming that you have already checked and know that you have a 10 bolt.

 

Yeah, it's a 10 bolt thank god! I'm going to stick with the stock rear drums since I'll be doing alot of power brake burnouts. Lol! Hey, thanks for all the help.