2000 Explorer 4x2 rear differential

I am experiencing excessive "road noise" when driving. Noise begins about midway point to the rear axle. Vehicle has 77,000 miles on it. Dealership said that rear differential may need "friction adjustment"? The tires have been rotated regularly. I had a tire/lube shop look at vehicle and they indicated that there were no leaks (besides freeze plug) and all u joints looked good. Ford dealership conducted 60,000 mile inspection and all was good. Can a good mechanic perform this service on rear differential and what exactly would be done and approximate cost?

you can buy a 7 ounce tube of "friction stabalizer" at Auto Zone, or other after market parts place. Says it meets the FORD spec on the tube. If you wnt to go cheap, put this into the 1/2 inch pipe plug "fill" on the rear axle center pumpkin.-- If you are more ambicious i would drain and refill with new gear lube and add the friction stabalizer. i dont know which axle you have, but most do not have a drain plug. you would have to remove the sheetmetal rear cover (about 12 small 5/16 bolts) to drain, clean up everything, glue the cover back on with RTV, the refill thru the 1/2 inch plug hole with 1.5 quarts of gear lube and the stabalizer fluid.