well before i asked a question if i had posi cause i layed down 2 tire marks. i didn't try any of your test but somthing alittle funner. i went to a clean cement parking lot. i did 3 burn out. i need breaks and new tires anyways. not long ones but 3 short ones and on 3 of the 3 i left two tire marks. so i am 99% positive i have posi because u guys said i would not be able to lay down 2 tire marks frequently.

 

sounds like you do have posi.

if you have a 9 bolt you can test for posi this way also..

http://www.9bolt.com/

 

Might be a Limited Slip....

 

limited slip is gms name for posi, you either got it or you dont, and just cause you left two marks, that dont mean ya got it, you gotta jack the car up, spin the wheels, and see it they spin the same direction, or oposite, if its the same directioon then you got posi, or look at the axle code

 

Or ..once again...pull the inspection cover and take a look!

 

Check the RPO codes for G-80 (Limited Slip Rear). Also, with a 305
TBI and if its a Auto the Axle's gone to be a 10-bolt 2:73 with a open diff. GM did not normally install a Limited Slip on these base models unless it was a special order (TBI???).

 

pull the cover and look. leaving 2 tire marks doing a burn out proves nothing. if the traction lose is equall to each wheel and tire then you will leave 2 tire marks every time. go to a drive way put one tire in the grass and try a burn out.

 

i had a limited slip 2.72 rear in my iroc aND I LEFT 2 TIRE MARKS FOR ABOUT 75 FEET. THAT MEANS NOTHING AND BURNOUTS are just messin up the tranny. i put in a 10bolt w/ moser parts and have noticed 2 things..
1- no more inside wheel spin on tight coners under alot of power
2-no sliding from side to side when wet outside.

look at the rearend, jack it up and run the #'s under the ham.