Powertrax is crap. I sheared all the teeth off of one before on my Mustang. Plus it's noisy as hell.

 

Interesting, how long ago? How much power did the Stang have and were you running slicks?

I am not endorsing the Powertrax because I haven't used it myself but they have 2 models, the noisy locker and the syncro'd no-slip. My guess on the shearing problem was either an alloy problem or partial engagement and impact load. I would be very surprised if a fully engaged unit would be the weakest link due to the total surface area of engagement. Again, not endorsing, just discussing. I don't know what changes may or may not have occured but since Richmond Gear just bought the company they must have seen something they like. Here is an email response:

"Switchboard [switchboard@richmondgear.com]
Powertrax was rently purchased by Richmond Gear. The number one priority is to get inventory on current models and then check intonew applications. Sorry, we cannot give you a date at this time. The Lock-Righ units are a bit noisy on turns, but the No-Slip units are quiet.
Dean S./j"

So, the no-slip unit that has syncros are quiet. The syncros should also prevent partial engagement that would lead to shearing just like in a manual tranny.

BTW, many high powered cars have failed torsen type gear LSDs... Clutch and cone types are also prone to failure. I will try to find out more on the Powertrax as the syncro'd unit may not be "a piece of ..."