Hi,
I had the same noise that started around 5k Miles.
its the FR L. Drive shaft that goes into the diff that makes that noise.
i noticed whenever the suspension traveled in or out it stopped making that noise.
so I decided to lift the truck and see what happens!
guess what the sound is Completely goneCompletely gone
so I suggest you all buy a 40 inch lift kit from ready lift and the sound will go away