I recently started hearing a weird grinding/howling noise coming from the rear end of my 98 cobra, it really doesent matter what speed as long as its over 20mph it still makes the noise, especially louder at highway speeds, If I am cruising on the highway it will make the noise and if i let off the trottle to coast down hill the noise will go away for a few seconds and start back again on deceleration. Any Ideas on what this could be? Pinion bearing?