I was watching HorsePower TV today and saw them use this active differential in a black convertible mustang and I did not caught the name of it but it where they could lock the rear up when at the track and with a button switch it off for regular driving.
I saw that show today too. I can't recall who made it, but go to www.horsepowertv.com. I think they have a list of stuff they did on a show that you can check out.
It is ected or something like that not active. It works with a magnet to put it in full lock mode. Supposidly it works very well. The only complaint that I saw about it was you can't put it into lock mode without being stopped(under 3mph i think) I think it is too expensive for what it is
Check out the electrac in the link provided - it's available for the 8.8; it's a regular limited slip in normal operation, and at the flip of a switch (electromagnetic) you can lock it completely up.
The Auburn ECTED unit is $584.99 through Jegs. It's a Limited Slip when it's "off", and a full locker when "on". You can lock or unlock it at any speed.