I've gotta do a better street test but I did a short brake stand in the driveway and only one spun...the passenger side rear. My experience in the burn box at the drags is that pass side rear will spin then the driver side will catch up. Kinda sucks. I'm told I'm probalby too heavy and powerful (over 700 HP to the tires) for a stock trac lok. Mine came from Ford Racing so it should have the carbon clutches...but doubtful it has the extra 2 clutches. Also doubtful it was set up tight. True Trac has been recommended at about $580, I did look at Torsens but they're more like $700.