Victim is a 2000 f150 xcab 4x4 5.4

I have a squeal/ grind I can't figure out. It sounds like nails on a chalkboard or a high speed wind whistle. It never happens when turning right, almost always when turning left. When going straight it kind of wheeps like a bad u joint. It is speed related and does not go away when braking. To try to fix it I have replaced both half shafts and both hub assys. This has not helped. I also checked the breaks in the front and everything moves as it should. I guess I have a few questions:

Could this be something in my front diff?
Or rear diff/ bearings?
Or Something weird like u joints?
Or ????

Any thoughts?

 

Or clutch packs?

Anyone?

 

Well i dug into the rear axel. The e- brakes that i rebuilt last fall failed and were rubbing on the rotor. The spring clip that holds the shoe in place snapped. New hardware kit and I should be all set

 

Glad you found it Hornsurgeon
Really hard to help someone with a noise on here