The rear end is making a noise like it needs bearings and seals.
A bad pinion bearing will make a howling type sound from the rear end if it is failing. Wheel bearings at either end of the differential will have the classic growling sound coming from either side of the rear differential. So depending on the sound that can indicate which bearing is failing. In extreme cases of pinion bearing failure the drive pinion can become loose and will develop play. If this happens, the pinion seal can be damaged and oil may leak from the front of the differential. You may want to enlist the help of a mechanic, such as one from YourMechanic, who has the training to check the differential and determine the proper course of repair.
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