Turn the yoke and if both wheels turn in the same direction then it's LSD. If they turn on opposite directions, then it's a open diff or one wheel peel.

 

best way to tell is to pull the cover and look for the clutches in it. you could spin one axle and see if the other spins the same way which indictes that it is a limited slip. but if it is worn and the clutches need replaced spinning one axle won't tell you a damn thing because a worn limited slip will act just like an open diff.

 

Ok. Good to know. I do not have the rear end though. A guy a couple hours from me does. So I was wondering if there is a way to tell from the tag before I drive all the way out there.

 

Have him turn the axle to tell you which way the wheels spin, have him take the diff cover off and snap a few pics for you, or you just might have to make the drive if you really want it.

 

for everyone saying turn the tire or turn the axel:

a LSD is DESIGNED to have LITTLE TO NO effect under low load situations. if it is working RIGHT, then it will feel/turn just like an open diff.

saying that, my lsd would spin both tires forward in neutral if i turned one tire.
about 20% of the time.
by spinning the input to the diff bolth tires will ALLWAYS spin the same way unless you got fucked up bearings or spiders