My old rear end was howling by the time I took my car down the dragstrip a couple times after I first bought it and in stock form, the previous owner had some issues but he had it fixed thru warranty.
So I bought the Ratech Deluxe kit from Summit for like 110$ and had it installed and I havent had an issue since. It was a quality kit and install too! I recommend the Ratech kit personally, I am very pleased, now I just need to upgrade to a taller gear...