How do i id my rear differential ?
It's a 2000 5.3 Z71

Bert

http://tinypic.com/ei2g51

Should be a sticker in the glove compartment with codes for a bunch of stuff. Can't remember which specific ones refer to the diff (or if they were labelled). If you can't figure it out, post back, and I'll check mine at lunch.

Probably the G80 (GM's GovLock) which is a limited slip unit.

In the glvoebox it will have the code G80 if you have this.

The G80 used in trucks today is a locker. It automatically locks when one rear wheel spins a certain % faster than the other. It will only stay locked 20 miles an hour and under. When the G80 is not locked it functions as an OPEN diff. It is NOTa limited slip. Check this out at WWW.traction.eaton.com/prod2.htm

Have a great day,

Don:)

In the Quadrasteer at least, the G80 is both. Mine chattered until I put in the limited-slip additive. Check any Quadrasteer forum, and you'll find numerous posts about getting the right fluid from the dealer.

What I meant was, do I have 3:42 , 3:73 or 4:10 ?

Bert

http://tinypic.com/ei2g51

Same place - glovebox sticker. I know GT4 is 3.73 (what I have), I think GT5 is 4.10, not sure what 3.42 is.

I have a question about this. Mine says GT4...Is this a limited slip and when I change the fluid should I add a tube of friction stuff? I can feel chatter when making a slow turn.

Friction modifier (GM Spec No. 1025358) is NOT required for centrifugal locker type limited slip differential axles.

Thanks Blue Bowtie; I guess I have a limited slip diff. I'll just change the 75-90 syn oil and call it a day.

3.73 is standard equipment on Z71s which is code GT4.

GT5 4.10
GT7 3.33
GT8 4.10
GU2 2.73
GU4 3.08
GU5 3.23
GU6 3.42
GV2 5.83
HC4 4.56
HF8 4.88

Most likely you've got the GT4, but you could also have a GT5

My 2005 only had two choices in ratio option 3:42 or 4:10.