How do I know this 89 280XZ rearend is LSD

Hi - I recently started having vibration issues w/ my 510. I put the car on jacks and found the u-joint on the halfshaft loose. I looked at the junkyard and realized my 510m had aZX rearend. I found a ZX with good halfshafts. When I spun the wheels they both rotated in the same direction. I removed the cover and inspected the gears. They looked good and moved freely. There is a circular disk on one side. Is this the clutch? I dont see any cluthplates or springs. Thanx, Tim

You weren't making any sense to me..but I'm going to try to answer your question...to the best of my knowlege..and then maybe somebody that knows more will give you a better answer.

In my experience there are 2 good ways to tell if a diff is an LSD.
1: Put it up on jack stands and rotate one tire, if the other turns the same direction it is an LSD. if they turn opposite directions is not nesessarily an open diff or an LSD.
2: Put the car on the ground, get everything out from in front of it. Start it up. put it in first, rev it up and peel out, if both tires spin you got yourself an LSD, if not you most preobably don't.

Hi - I recently started having vibration issues w/ my 510. I put the car on jacks and found the u-joint on the halfshaft loose. I looked at the junkyard and realized my 510m had aZX rearend. I found a ZX with good halfshafts. When I spun the wheels they both rotated in the same direction. I removed the cover and inspected the gears. They looked good and moved freely. There is a circular disk on one side. Is this the clutch? I dont see any cluthplates or springs. Thanx, Tim
Thanx for the reply- I found out that if you lift 1 rear wheel by jacking up the side of the car, the wheel should not spin. If it does, that means your rearend is not LSD. t