'04 3500 Duramax srw crew cab longbed. When I make a turn in my truck I can feel and see the inside wheel slipping. At first I thought I was just gassing it too much but then I found that it always did it, even when turning in reverse. Sometimes, I'd say 50% of the time, when turning I can feel and hear a hard clunk from the rear end.
It's like the inside wheel is turning as many rpm's as the outside wheel, just like a locker. I can't imagine the rear end has a locker, I would think it would have positrack but it still doesn't explain the loud clunk. Any ideas?

 

change the lube and py possi additive from GM not from autozone i would start there!!! rule out cheap stuff first!!! this is a common thing suppose to change rear end fluid every 30,000 miles

 

so would that be why my limited slip rear end has no limit to it its all slip?...

 

Posi and limited slip both need that special additive for the clutches to reduce friction on the clutches!!

 

After reading through some other posts there seems to be some confusion on whether the additive is needed or not. By no means am I saying you are wrong, just trying to learn as much as I can. Why would you need an additive anyway? What spec. of lube is recommended? Are there aftermarket lubes, additives that are better than oem?

 

I am 110 percent sure you need the additive i have done may rear ends!!I know lots about them!! You need limitedslip/possi additive if you do not beleive me that is your loss!!

 

the additive reduses friction on the possi clutches use 80/90 gear lube i prefer lucas oil and use the gm additive do not buy the cheap stuff at autozone!!!!

 

I got home from work and in a hurry I started draining the diff. My intentions were to take the cover off and inspect but a nasty cold storm blew in and started dumping on me. I was able to drain the old fluid, it was black, and replace it with Lucas and the gm additive. My wallet felt some pain when I looked at the drain plug and there were two tiny teeth on top of it. About the thickness of a toothpick and about a 1/4 inch long. I did the best I could to scrape the bottom through the drain plug but found no other metal bits. I stuck my finger in the hole,lol, and felt the bottom of the diff. My finger had stripper sparkles on it when I wiped it off. (tiny metal flakes like dust) Took it for a spin around the block and then turned into a parking lot so I could do some turns. Damn it! The wheels still skip!!! I turned the wheel all the way to the left and watched the left rear tire come to a complete stop when I let off the gas. I slowly straightened out the front wheels and the truck started rolling again (it's an automatic). Why would it bind up like that?
I replaced the u-joints and the carrier bearing on the two-piece driveshaft about two months before I had this problem. That wouldn't have anything to do with it, would it? I really need to find out what's wrong but at the same time I need to find out WHY it went wrong.
Broken truck=no fishing....it's a sad day.

 

Wait you replaced the carrier bearings in the diff? To me sounds like you need a new ring and pinion and or new clutches in your possi

 

No no no, I replaced the carrier bearing on the driveshaft. It's a two piece shaft.

I'm done driving it...I don't know how much it's going to cost but I'm going to get it fixed, whatever "it" may be. Hopefully it's an easy fix but I'm sure it's going to cost me. I'll let you guys know what I find out.