I bought an Auburn posi trac differential that was slighly used. It was for a 8.5 10bolt 30 spline axle just like what my 1999 (NBS) is correct? The guy sales alot of these diff's and said the only difference was that i needed to install new bigger carrier bearings for my truck because it was the newer body stlye. I got the carrier bearings and races from Oreily's. I just got a call from the guy at the shop installing my rear end and he said that the carrier bearings were too big! So what do you guys think is the problem? Oreily's gave me the wrong size or what? Or is it a bigger problem than that. Does anybody have any part numbers? (They were federal mogal).

 

found this off of auburn's site

part # 542097

8.5 & 8.6, 10 Bolt
All GM products with 8.5 & 8.6 ring gear
Uses LM60349 & LM60312 diff. bearings
2.73/up
30 Teeth
1999 - Present

 

what part number did you get? i'm going to work at noon and i'll look up and see what it calls for, your rear diff is for a 99 nbs right? if you can, get the shop to pull the old bearing and see if they can find a part number on it and call oreilly's and get them to cross the number, or just get the shop to get you the right bearings

 

Thanks alot. I'm fixin to head to the shop and get the old ones and then head to the auto parts store to see what i can do.

 

Im fixin to make a trip to try to get all of this sorted out. I won't be back by noon though. So if i still have problems i'll shoot you a PM. Thanks

 

I hope you aren't paying money to get a g80 installed although I'm pretty sure that's what you're doing since you said you have an auburn differential.

 

I thought the Tx. education system was pretty good.....

 

I think Mark is having a few beers with lunch.

 

Well, I swung by the shop and checked out the bearings and i think i have a much bigger problem. The bearings were too big and from what i can gather they are the correct bearings for a stock rear end but maybe not this auburn? I bought the diff. from a guy on ebay who sales alot of them. A couple months ago when i bought it, i posted and said that the seller said the difference in the 99+ NBS rear end was that the bearings were bigger and needed to be replaced. The responses i got from guys on here matched up so i thought i just needed the bearings for the newer trucks. Do the auburns posi trac diff. not use the same bearings as the stockers? The diameter of the places where the axles enter the differential is actually smaller than that of my stock unit. But as long as they're both 30 spline shouldn't it be the same?