Hello guys i have a 03. F350 4x4 7.3 auto locking hubs.No noise when driving in 2wd when i put it in 4hi starts a grinding and howl noise seems from the left side faster i go louder it gets.I went under the truck and spun the front shaft and it was easy no binding or anything so i locked the hub manual and both locked.Truck only has 85k on it any ideas? Thanks

 

sounds like it could be a hub or maybe the transfer case try to listen where the noise is coming from