Ok so i have warn hubs on my 01 7.3 when the hubs are locked i get a bad grinding noise/ rubbing noise. It sounds like a the driveshaft is rubbing something. At first i thought it was the grease zerks on the ball joints because they were rubbed on. I replaced with smaller zerks and the problem is still there. I noticed that one of the vacuum seals behind the hub is ground down a little bit. Does this sound like it could be my problem? The noise is very loud i can hear it will my windows up and radio playing. Any thoughts?