Heard back from SC. Turns out the problem all this time was with the rear DU, not the front (which they replaced). Now I will have new front and rear DUs!
Rear DU was replaced, so now I have new Front DU and Rear DU. The whine at 49-51mph is still present, maybe a drop quieter, and there is a new whine at 31-34mph which is as loud as 49-51 before...
The rear DU part is: ASY,DRIVE,UNIT,3.0-150,REAR (1037000-
00-F)
