im gonna go check out this guy's 87 GXL rear end in hope of finding a quality LSD for my 87 SE. you guys know any tests i could run on it to make sure its working correctly? i dont want to invest in something thats broken and i dont really know what to inspect.. thanks in advance!

 

jack car up. turn wheels. look see if other wheel turns same way.
yay it and LSD. aslong as wheels go close to each other than its in good shape

 

My friends NX2k has LSD (factory supposedly) we jacked it up, turned one wheel foreward and the other turned the opposite way.. Same happened to my car, and i know it doesnt have LSD. The Nx2000 is FWD though so does that have anything to do with it?

 

thanks so much for your constructive comment dezerte

 

did you spin the back wheels or the front wheels? the lsd only acts on the wheels that are powered.

 

On the NX we spun the front passenger, on my FC3C we spun the rear passenger, same results both times. Other wheel spun opposite, his car has LSD mine is open diff.
NX = fwd
FC3C = rwd

 

maybe it was a viscous coupling?

 

You are correct

 

if it has a viscous lsd then it will appear open until it is under a heavy load.

 

Unfortunatly the spinning the wheel thing will only confirm that there is a LSD in there, not that it works. My lsd on my 86GXL recently went bad. If you jack it up it still acts like an LSD, but it will spin the crap out of the inside right tire in a hard turn.