I had the flush and refill done today.
#PI0137: Rear Axle Chatter-Type Noise on Low-Speed
Turns
The noise started several weeks ago and was getting worse, so I took it in. So far so good.
FYI -
The service tech said if you catch it in time it should be good, but if you wait too long the damage would be perminant and the center section would need to be replaced. So far he has replaced one (15,000 mi.) all others 5k or less the flush has done it.
If you hear it - take it in.