Limited Slips AKA Posi'* work quite simple actually.
Stock your differential is "Open" style.
I've been wanting to get some product info on FWD Aftermarket LSDs, however, not many companies make them, Auburn Gear does I belive, I know Detriot does not.

That dependson which type your talking about..
A spring loaded clutch type diff (like Intense) is simple but other types such as a torsen diff are much more complicated.

Not to mention the cost, btw.

Turns out the monte has some burnt trans fluid with a big leaky leak. So no more fooling around in that car... god knows how much that kid did anyways. I'll do the spin trick next time he brings it in the shop. Just to confirm, posi would spin both wheels the same direction?

Clutch type yes, Torsen may not.

The best way to tell if it has a limited slip is to jack up the front end with both front wheels off the ground.
Put the car in neutral with the engine off.
Rotate one wheel by hand.
If it has a limited slip, the opposite wheel will turn in the same direction.
If it is standard, the opposite wheel will turn in the opposite direction.

Well, a funny story ends it all. The monte kid keeps telling me he wants to race and that he'll smoke me.. which is probably true. But anyways, he pulls out of the shop today, only to find what, about .5qt of black trans fluid. Not only does he have some very burnt fluid, it'* coming out of the gaping hole in the diff. We looked into the giant hole, and sure enough, no posi. Just another open diff :(

You guys were right, no posi. I was getting excited... sure would have loved some posi on the bonne

Not sure if this always is true... my truck'* limited slip needs 100 rpm difference between wheels to kick. and when you rotate in neutral..they act like a standard open diff.

Kick it in the guts and it'll lock up ...

Bill, you have the GM stock LSD varity, we refer to it as "cooco clock LSD" if you look inside of it, its insane, few springs, little cams that lock up and such..bizzare set up

How much traction do you need with fwd and a LSD? Isn't the engine heavy enough? Too bad all these cars are fwd, I have a Detroit full-carrier locker in the rear of my Jeep and that thing is painless and bulletproof...