Replaced rear end at my cost, after warranty, very low mile garage queen. Pampered and driven like a person my age, 75. Have about 8500 mi. on the replacement rear differential, and the whine is back! It will get louder as I add the miles. This should be covered on recall, period. Now I'm hearing, Cadillac isn't making the part anymore, so even a $5000 fix won't be possible. I've owned quite a few new Cads, this is the first I've had problems with, and frustrations to correct. Love the car, but not worth the anguish. Sorry to say, it's my last Cad. If you have one that hasn't lost a rear differential, email me, love to know someone got a good one!