Alright, so here's the story. I finally found the gears and posi I've been looking for for a while, so the other day I ordered a ring and pinion install kit. It came in the mail today and I was looking it over when I noticed that it said it was for '77-'81 7.5 10 bolt axles.

What's the difference between the really early 10 bolts and the post '82? Is it something simple I can just pick up locally, like a crush sleeve or pinion bearing?

I tried calling Summit, but the customer service rep just told me to call Richmond to find out exactly what is different.

Please help me get my car going!

 

The "old" 10 bolts are 8 1/2", the "new" ones are 7 1/2" or 7 5/8". The only thing they have in common is that they both have 10 bolts. Absolutely nothing interchanges between them.

 

I'm pretty dang sure there isn't a difference. But i don't know EXACTLY. You could probably ask a shop that would install it or does axle work if they know the difference. I'd say as long as it's for a 10 bolt, there's no difference, but don't hold me against it if i'm wrong.

 

Your 8.5" install kit isn't going to work for a 7.5" diff. You have the wrong kit. You might as well have received a 12 bolt kit or a Ford 9" kit.

You need a kit for a 7.5" 10 bolt diff.

 

Well, you ARE wrong. The question was answered in the post before yours.

 

you'd think the 77-81 gm 10 bolt tag would of been a clue that there is in fact a differance

 

No, it's not an install kit for an 8.5 10 bolt. To be more precise, it's Richmond Gear part number 8310161, Ring & Pinion Full Install Kit for GM 7.5 10 Bolt 77-81.

Inside the box are two separate packages of parts. The package with the bearings, carrier shims, pinion nut, and ring gear bolts is marked 77-81. The package with the cover gasket, pinion seal, pinion shims, and crush sleeve is marked 81-91.

So it looks like I can use the cover gasket, pinion shims, pinion seal, and the crush collar. But what about everything else? What's different?

 

yeah looks like you can use the install kit, but not the gear set

 

I only got the install kit from richmond. I got the gears somewhere else.

 

ok you have 2 intall kits, use the one for your rear and return or sell the other one. it also sounds like someone mixed and matched parts and sold you something that won't entirely work for your application

 

Well, I did some more searching and found out that they changed the pinion head bearing from 3 inches to 3.125 inches in '82. Simple enough, I just need a new bearing.

 

If you can't tell the difference, then you have no business doing the job yourself. Do yourself a favor and take it to someone that knows what they're doing. I can already see your next thread......"installed my gears, now they whine real bad. Was I supposed to put the shims back in?"