This is old, but I just pulled out the rear the other day and I figured i'd give someone a heads up if needed. I bought a 3.91 rear from hockdane during the summer last year. I drove a good distance to get it, and I should've known once he pulled the cover to leave, but I needed a rear. I never smelled gear oil like that and i've been around more then one rear. Needless to say when I got home I installed it and it whined badly at highway speeds, and the posi was worn. I was lead to believe that it was a tight posi with low mileage, and it wasn't. The calipers were seized and the rotors were junk, but I didn't care about the brakes.
His response to my aggrivation was this "i'm still not sure why it only left one line. that posi has gotten me in a lot of touble in the rain when going around turns. personally i still think you made out well even if the posi is worn: you got a quite rear with better brakes and better gears in it. i think you still made out well.".
I guess I made out well for 350/400 I got a useless rear, not to mention my driving time/gas.
From now on i'm going with my instinct, and you shouldn't trust anyone that's stupid enough to get under his car with inadequate jack stands, that shows what type of person you're dealing with in my mind. His car was up on stands when I pulled up, and they were cheap garbage.
I'm thinking he didn't know that you have to actually set a preload on the bearings or it's a backlash issue with the wine.
Once again thank you if you read this.

Here's the link if anyone cares:
https://www.thirdgen.org/forums/engi...tml?highlight=

 

that's too bad that the posi was junk but the 3.91's are a very hard gear set to find. If I had seen that post when I was still in Maryland for the rear I would have jumped at it plus I had some 9 bolt parts from when I was planning to keep it like 3 series carriers.

 

Yeah it's too bad. I though he was wrong, I never saw a 3.91 before then. I could just sell it right now to someone, but I want to find out what was wrong first. I'll probably keep it though. I seem to get screwed often, as do we all by our wonderful honest government.