whats in my z71?

ight when i first got this truck (2000 1500 z71 silverado with 5.3L) i thought o cool z71 so it should have a locker or posi in it, well when it was still stock (dont do it on my 35s cost to much lol) and if i spun wheels the only the right would spin so somewhat disappointed i figured i had an open diff and i looked up the g80 locker thing and in my vin i dont have that ether so open diff im thinkin, well latly i powerbraked it in my friends lawn (he was cool with it lol) and both back tires turned over no problem and this was with 35in mud terrains, well want i want to know before i buy anything is do i have some sort of posi in it or limited slip and its just worn out or what? or can an open diff spin both in the dirt? and ive been stuck in the mud with this truck were one tire was on firmer ground then the other and the one with least amount of traction spun, o thinkin open diff there fore why i got stuck : \, so does any one know what i might have or know what these trucks came with? if i just have to rebuild a worn out posi or should i invest in a locker or something? thanks

the eaton locker used on these trucks will not lock up until slippage is occuring...then the both axles lock as one,,no slippage as the limited slip car diff will do....

I have found that the rear diff cover must be removed and the diff cleaned when replacing the diff fluid...
when the fluid goes bad the diff tends to lock slower and this then causes the engagement to be harsh....if you have the eaton locker the tag on in the fill plug area on diff will state use synthetic 75-90wt ...only..
also the glove box will have a label showing the diff code that is installed..

with the limited slip you would add the 4oz of additive to the 80-90wt,,but not on this diff..

if the diff is in need of replacement you must break in the diff with driving the vehicle very easy for a 1,ooomi...then replace the diff oil.....the teeth must be hardened properly and if you drive it hard the teeth will get brittle and crack break off...the diff also gets very hot on the first 500mi so don't go for a long drive...with the high temps created this then requires oil replacement and with the cover removed you can inspect for proper teeth alignement and debris removal...[clean magnet]

yeah i was thinkin about pullin the cover off and cleaning and lookin at it, i know i dont have a g80 cause its not on the fill cap and its not in the vin and i can spin one tire for as long as i want the other will NEVER turn over unless traction is changed, always notice it off road, im thinkin i have an open but some one told me these trucks came with a posi if it didnt have a g80 so, idk lol

yeah i was thinkin about pullin the cover off and cleaning and lookin at it, i know i dont have a g80 cause its not on the fill cap and its not in the vin and i can spin one tire for as long as i want the other will NEVER turn over unless traction is changed, always notice it off road, im thinkin i have an open but some one told me these trucks came with a posi if it didnt have a g80 so, idk lol

you don't have limited slip because both wheels are always in limited slip mode,,,,not a good design....especially if GM did/or someone installed a limited diff on a truck...you most likely have an open diff...with what you stated on the vin/and glove box codes...its open...

ight, what i thought but a couple of people said its a z71 so its got a posi, uh well lol detriot locker here i come lol