chiefy9

This one kinda has me stumped at the moment and wanted to ask around here before I took it somewhere to have the put it on a lift and see where it's coming from. Basically it's a grinding noise only when accelerating. I recorded the noise and put it on the tube so yall could hear it. It only happens when I'm accelerating once I'm at a stable speed it goes away doesn't matter how slow or fast once i'm done accelerating it's just like it never existed. It doesn't occur from turning either. Any help would be appreciated. It's about 85% reproducible as well doesn't happen all the time.
https://www.youtube.com/watch?v=CO47...ature=youtu.be
5.3L
1500
4wd