I have now owned 3 f-bodies, 88TA, 97Z, 02 SS and all of them had whiney stock rears....so don't worry if the 12B whines a bit, just make sure that they set your pinion angle right, they you should be OK. Also at 3K miles from now, change the rear fluid, go to 120W oil and limited slip add if you got the limited slip diff. If not then use full syn gear oil.