what can cause a rear axle to shift?, i have found that mine is 1/2 inch to the left.... and causing rubbing on "extreamly hard turns" and is there away that I can prevent this?
all the stock rears are more to one side. Get an adjustable panhard bar, Hang a string (about 10 inches long) with a weight hanging. Tape it to the outsidefender/wheel opening about center with the wheel. Do this to both sides, then adjust the panhard bar and check with a measuing tape untill both side are even.
Yeh you need a panhard bar or at least new upper and lower control arms. Personally I would get stock replacement uppers unless it is only being used for drag racing. Get lowers with poly three piece bushings.
Well I just got mine back under the car today and mine appears to be off but will see when i get it off the stands and suspension loaded. If you are saying yours is a 1/2" diff that actually means a 1/4" because if you move it a 1/4 one way you plus that on one side and subtract from the other side so it is only a 1/4" off center and that's not too bad.
Do you have uppers already? My uppers shifted on me after I went to the track. I had to get under the car and tighten up the adjustable uppers really tight. After that I had zero problems with the car.