2002 F-250 7.3

[JPOWERStroke53]

I have a 2002 4x4 7.3 psd, that I've been having problems with that don't seem to be getting any better with everything I fix. It is lifted about 6 inches and has 35's. I started noticing a grinding sound when I let off the gas at about 60 mph. It is now starting to do it more even when accelerating at times.
Also at times it squeeks extremely loud at real low speed take offs, like when just letting the truck pull forward with no gas applied. I've been stumped on this. New hub assemlies all the way around, new calipers and brakes. New U joints at the knuckles and in the front and rear drive shafts.

I am stumped. Ive taken it to shops to look at it and they arent too sure either.
Someone please help me.