See the following thread that I started a few days ago:
Please! Help kill the mouse under my 1989 420SEL
Seems like we're all having the same problem!
David, did replacing the bearing and hub actually fix the problem for you? Or do you still have the squeal DESPITE the repair work? (It wasn't clear from your posting.)
I ruled out the brakes as the cause, since I had mine done (rotors, pads, and calipers), and it made no difference: The whining persisted.
If indeed the bearing/hub replacement solved the problem, may I ask if it was an expensive fix?
Thanks for responding...