I had my posi rebuilt and put in. Car was fine for a day until I was shifting from 2nd to 3rd at wot and the rear locked up solid and the car was basically dragging the rear. I backed out into neutral, and it did the same thing until I slowed down to 40mph and dropped it into 3rd. Coming home after that, going downhill, not accelerating, shift to third, rear locks solid, card dragging the wheels. This is crazy dangerous, I almost died the first time as the car fishtailed back and forth. Any idea? It has all new clutches. I was reading it might be a bad spider gear?? 96 cobra... Please comment this is bad and I have no desire to wind upside down in a ditch.