I've got a 2000 Dodge Dakota that is making a high-pitched whine from the rear axle. It's the "heavy duty" option 9" rear end WITHOUT limited slip. Has 96K miles on it and the fluid looks pretty clean. (I've only had the truck for the last 12K) It starts as a slow whirring sound around 20MPH and increases to a whine at highway speed. The noise changes little with acceleration and deceleration. It's made the noise to some extent as long as I had it. I just thought it was gear noise. But lately it's been getting worse. I thought maybe I was mistaking tire noise, so put it up on jacks and ran the rear wheels off the ground...still does it. What do you think? Are the ring and pinion toast? Or maybe just bearings?