My 84 300 SD has developed a whine that sounds like it is on the passenger side of the car. It goes up or down with the speed but is not constant with the engine. If I coast to a stop the whine gets lower in pitch till stopped. I had new front brakes and bearings in august and new tires in oct. I have rotated the tires and no change. Any one with a clue please point me in the right direction.