Recommend starting out with a visual inspection. Some rear-end parts are easier to replace than others.
A lot of information can be gleaned from the details of the noise. For example a growl is usually wheel bearings. Does the noise happen when driving or coasting? Turning or going straight? Is the noise high/low pitched? What speed/gear does it happen?
Wheel bearings are fairly easy for the home mechanic to replace.
A whine could be carrier bearings, pinion bearings, or incorrect back lash.
Replacing carrier bearings needs a shop press but 98% of the work can be done in the driveway.
A pinion bearing is more difficult for the home mechanic to replace. It can be done but recommend that you do the homework.
Bottom line, many rear end problems can be diagnosed with a visual inspection. It will not get better on its own and in fact may do additional damage if allowed to continue.
Start by removing the rear cover. Inspect the oil. Look for small bits of metal in the sump.
Take out the half shafts and inpect the roller surface. Replace if scored or pitted.
Look at the wear pattern on the ring and pinion teeth. Take the carrier out and look at the bearing surfaces. Pay attention to ANY pits or blueing of the races. Closely look at the bearing rollers. Edges should be rounded. Replace if wore down to sharp edges.
Good luck.
