2006 2WD with 200K miles. It has developed a whine, increases in pitch with speed. Accelerating, I begin to hear it at about 20 mph. Decelerating, I hear it almost to a stop (more of a growl at that point). No vibration. Been doing this for at least the last 5K miles. Is somewhat louder now than when it began. I believe it is coming from the rear, however I can't say for sure. Would appreciate advice as to where to start