I have a 2000 dodge durango. There is a whining soud coming from the rear end. The sound is only present when I am accelerating. If I let off of the gas and coast the whining stops until I accelerate (and it doesn't have to be a lot of acceleration). Any clue as to what this is? I changed my rear end fluid and there wasn't any metal shavings to suggest that the gears are grinding.

 

Usually when you start getting a whine in the rear end the ring and pinion are scalded. The ONLY way to eliminate sound is to replace the ring and pinion and if there not put it right, they'll whine again right from the start.