Probably answered this one before, but i know it's hard to find/search.
Depends on your intended use?
Street and strip - the Tru Trac is good. Good traction to both wheels. Seamless transition from open diff. to limited slip operation
On a race track - also good......however...as soon as you lift a wheel/ ride up over a ripple strip, no good, turns into a single legger.
This is detailled in their doco, i.e both wheels need to see some form of traction for it to lock up.
Pros - silent operation, no clutches to wear out. And it fits into Banjo axle assemble straight up. Fine spline version is prob. better for hard use, but then you are up for another $1k ish for a set of billet axles.
Cons - lift a rear wheel, and it's all over.
Sold mine and went for a Detroit Locker.
Detroit Locker -
Pros - once locked ( under power) , they are LOCKED. ( from my experience). Never have to worry about 1 wheel spinning. Fits straight into your housing.
Cons - rough as guts and noisey in their operation. Not particularly nice in a street car. On a track, all the other noise/helmet etc means you don't hear it.
Again, fine spline for hard work.
Hope that helps.