Exactly how much bigger is the turbo LSD to the normal n/a. I ordered a diff and i think the guy sent me a n/a diff rather than the turbo. I want to make sure there is an obvious difference before I say anything.

 

i searched and found what is posted 2nd post below. i found that quicker than it took me to respond to your question in the first place.

 

spin one of the splines and see if the other side rotates the same direction of the one you're turning.. my turboII diff is only slightly larger than the NA one.
another way to tell is if you have the halfshaft butt-splines (or whatever they're called) out of the diff, you should be able to see all the way through it. if its an NA one there is a bar in the way and you cant see through it.

 

RotaryResurrection
All 86-88 GXl, unless theyve been changed, have LSD stock. 89-91 do not.

There should be a small metal tag hanging from the backside of the diff, on one of the fill/drain bolts that says something about LSD fluid. Also, if you jack up the back of the car and put the trans in N, rotating one wheel should make the other rotate the same way. IF it turns the opposite way, it is a standard open diffy. Rotating the driveshaft should make both wheels turn the same way also, on an LSD.

Icemark
Please read the FAQ for FC at the top of this section, before posting as this question is covered there.

And as a note: Posi or Positraction is GMs name for a Limited Slip Differential (LSD). Calling a LSD a Posi, is like calling all refrigerators Kenmores.

 

The guy told me this was a 91 convertable, he also said it was a j-spec... so it had to be a turbo diff... well it isnt any bigger, i measured. makes the same clicking noise the one off my 89 gxl did... when I rotate one side the other spins the opposite. If that isnt bad enuf UPS slashed some of the bolts...

 

The TII differential will not bolt up to your NA driveshaft. Therefore, if it fits, it is a NA differential.

 

Well it is supposed to have been from a 91 convertable and have a 4.1 ratio...

 

well if you pull out the pumpkin you can use a ruler. The N/a has a 7" gear and the TII has a 9" gear i beleive.

 

i never thought about that.. american (A-spec!) convertibles have 3.9 rears. but if their convertibles are turbo, 4.10 makes sense.
have you found out yet?

 

where did you read that a-spec convertibles have 3.9 rear gears... i was under the impression (did the reasearch a while back) that they had 4.1 (at least my 91 5spd)

 

all j-spec cars are turbos... still waiting for him to e-mai lme back. on a side note, I was looking at it and UPS must have dropped it like 10 times or something, a bolt on the side is bent and the fluid bolt is smashed and has a large gash through it....