I believe mine is a 87 RX7 NON-TURBO. It uses clutch plates and you can shim it so that it is tighter. If you get a whole rearend with the stub axles, you can check the brake away torque with a torque wrench.
The one I have started @ 20 ft lbs and after shimming it, well guess the shim was too thick cause it jumped up to 90 ft lbs. I know that if you really work at it you can shove an extra plate in it and it will give you about 180 ft lbs which is like locked.
Think I will re-shim it and get it down to about 65 ft pounds. More aggressive than stock (40) but 90 seemed not forgiving enough.

Good luck, I got a whole rear diff with stub axles for $50 off craigslist. The ring and pinion were fried but the lsd plates were just worn.

Let us know what direction you go.


Everet