I have a Power Trax (VX-124A) locker in my Cuda's 8-3/4. It has seen a fair amount of track use since the year 2000. It does click when making turns, but I am OK with that. It came with two sets of springs; one stiffer for more track use, and one set for more street use. This car is over 3700 lbs with me in it and runs high 11's in the 1/4 mile.

1993 Daytona, 5.50 at 130mph (1/8) 1.19 sixty ft (PG). Link to 572 B1 - Part 1