SWHouston

You probably have an Eaton Differential in your rear Axel. It's sorta an automatic part time positrack...sorta. There's a little Tag in your Glovebox, which has what we call RPO Codes on it. Those are how your Hoe was set up with OEM equipment. Look for the sequence "G80", that means there's an Eaton installed.

But all 4WD in Tahoe or Burbs have a Locking Front Axel when in 4WD. Not limited slip, it totally locks both front wheels together. You should get TWO nice black marks from the front wheels, if you stomp it and make the wheels spin. Try that "Ditch Test" you did the other way around, with the Rear Wheels in the Ditch and see what happens !

BTW:
You probably have about a 3.73:1 Rear Axel Ratio (maybe). Now, when you put your Hoe in 4WD-lo, the Transfer Case makes that the equivalent of a 10.14:1 Ratio. How's that for POWER !

aris_unlimited

I've actually checked before and I don't have the stock limited slip for the rear, so I am guessing that 2 of those were from the front. Figured the front only had 1 tire spinning so maybe someone else put a lsd in the rear lol. Guess I am mistaken.

Although I do plan to put a limited slip in the rear end at some point this year.

73shark

Try for a G80 as it is a locking diff., not a limited slip posi.

SWHouston

Ok, I stand corrected, the RPO G80 locks (for a while anyway)

So, you're right, anything could have happened before you got your Hoe, but I'd do a lookup on what the RPO Sticker has listed, just to make sure you knew where it started. However, I can't see them putting 4WD in your ride, and not having the Eaton back there to help.

Below, I've listed several RPO Lookups. Reason for that is, that not all RPO Codes are listed within a single List. So, if you don't find the Code on one, look at the others for it.

RPO Code Lookups...
http://www.montecarloss.com/SSThunder/gmcodes.html
http://www.rpocodes.com/
http://www.angelfire.com/ny2/96transam/rpocodes.html
http://www.gm-trucks.com/rpo-code-lookup/ (reverse lookup)

PS:
I can't get my mind past you not having the Eaton. Maybe you could take your ride to a good Rear End Shop, have them pull the Plate and just take a look. If nothing else you could put fresh Lube in back there, if everything else was ok. At least you'd positively know ! Also, IF it did have an Eaton, and it wasn't operating properly, you could fix or get a cost of what $ that would take.

aris_unlimited

I've checked my RPO codes before and I know that it didn't come with it. If I am not mistaken the G80 only came on z71's. And I don't have a z71.

73shark

Std on LTZs also and I believe optional on the others.