2000 Z71 Limited slip questions

boosted88gt · December 18, 2003

Hi, i have a 2000 gmc 4x4 which i bought used, i went through the rpo codes in the glove compartment and i could not find one for a g80 locking rear diff,this is upsetting because i thought that all trucks with the Z71 package were equiped with a locking rear diff, full skid plates,46mm shocks etc etc. I mean there isn't much point to dropping the cash on the z71 package if it doesn't have a locker, this is the main item that makes it slighty more "off-road" capable. Is there any other codes i can use to find out if the truck is actually z71 equiped? is it possible the dealer did not throughly investigate the packages the truck came with, and somebody passed it off as having the z71 package, by slapping a couple stickers on it? Function wise it does not appear to have a lsd but im not positive, i know i could easily tell by popping the rear cover, but id rather not if i don't have to. Advice needed on how i can find out if it truely does have the off road package.

boosted88gt · December 18, 2003

oh btw it has a tag for synthetic fluid only on the rear, but that might be required for all rear diff's locking type or not.

SilveradoWV · December 18, 2003

If its a Z71, "Z71" will be one of the RPOs listed on the RPO sticker in the glove box, along with G80 if it has the locker. I am not sure if you can get a Z71 without a locker, it may be possible. But check that sticker in the glove box for the Z71 code, not the bedsides. Oh, my Z85 has an open diff and still required synthetic.

boosted88gt · December 18, 2003

yes it has the Z71 rpo, but sadly no g80, i don't know who the heck wouldn't get a locker if they buy the Z71 package, then it really would only be skid plates Oh well i'll pull the cover tommarrow to find out for sure unless anyone can come up with a better plan, in the case of no lsd ill just have to get ahold of powertrax

JayMan · December 18, 2003

Yeah, believe it or not, in 2000 you could order the Z72 "offroad" with an open diff. The G80 "locker" was an option when I special ordered my truck. All 2000's LD trucks require a synthetic 75W-90 GL-5 gear oil, with the G80 the gear oil also needs special friction modifiers.

Easy way to tell without pulling the rear cover off is to just jack up one side of the rear axle and put it on a jackstand. Now see if the truck can drive off! This is also a good way to see if your G80 is working right, as on pavement, cement, or hard ground the G80 is quite capable of driving off the jackstand.

Actually, the PowerTrax NoSlip might work better anyway. At least you will never have to worry about limited slip additives like I do. The correct NoSlip part number is:

92-0786-3005

I think you can also get an Auburn Gear unit too. Good luck!

99silveradoz71 · December 18, 2003

I am not sure if you can get a Z71 without a locker

My 99 has an open diff.

Mega Dogmeat · December 18, 2003

"Z71" is basically just a tool for dealers to try to get higher markup out of vehicles sold from what I can tell. I think this might have changed in 2004, but I could be mistaken.

Anyways, it's ultimatley a $300 decal.

seadoons · December 18, 2003

The Z71 package adds skid plates, different shocks, the sticker, and some sort of "jounce" bumpers - basically a $300 addition to a 4x4 truck. On my 2002 the G80 was an option, and so were the 265 Firestones, fender flares, etc etc. The Z71 package doesn't do too much for you...

99-2door · December 20, 2003

I will try to avoid getting into the whole "what are Z-71s available with" argument.

But they were/are available with or without G80 locking differential. Check for the RPO code, if it's not there it wasn't originally equipped with it.

Common misconceptions are:

Z-71s all have G80

Z-71s all have auto trannys

Z-71s all have 3.73 or lower rear diffs

(I had one truck that disproved all 3 of these, a 95 Ext. Cab 5.7L 5 speed with 3.42s open diff)

All Z-71s are short wheel-base