I have an 01 F350 DRW, 4x4, 7.3l PSD with 48k miles. While driving you can hear a grinding type sound coming from the front end. At first I thought it was a ball joint causing the sound as my left front needed to be replace. So I went ahead and replaced the front brakes pads, calipers, rotors, and ball joints (upper and lower) and the sound still exists. The shop that replaced the ball joints checked the bearings and said they were good. They did some additional checks and said the entire front end and suspension are in good shape. Any thoughts on what could be causing the sound?? Thanks!