Even with a locker they spin? Sounds to me like you need to get a Eaton posi.
But as far as the track goes, these won't ever be going. I got these mainly for daily driving. Its odd though that they are not working well for you, they were ranked with having some of the best traction on the market.
FOR ALL YOUR WHEEL, TIRE, AND ACCESSORY NEEDS
CONTACT: EPLEY'S TOUCH OF CLASSIC 1-270-843-6892
OR TO GET ME PERSONALLY CALL: 1-615-943-6514
2000 Chevy Silverado 4.8L RCSB: smoked UPD, Flowmaster exhaust, De-screened MAF, Nelson 93 hot tune. Upcoming installs: trans-go shift kit, Eaton posi, billet servo, ported and polished throttle body...Near future: 6.0/4L80E install with 150 wet shot