Noticed a slight whine when coasting down to a stop for the last couple of weeks. At 138000 miles, I narrowed it down to the driveshaft carrier bearing. My trusted mechanic got it up on his lift and we verified that it was indeed the drive shaft. RockAuto only had 4wd shafts, not for the 4.0/2wd...
Look on the bottom of the door, there is a plastic/steel looking clip on it. Get a screwdriver pop those things off. Dirt and sediment will drain down between the windows and doors. Takes a long time, but it will happen