It definitely sounds like something is loose. You probably have a lift, so it could be a variety of things, even something associated with your driveshaft. I would initially check anything regarding the suspension that is not stock and make sure all the bolts are to torque specs.
The problem is that this is just too vague to diagnose. There's so many different possibilities, you're just going to have to check them very, very thoroughly. All it takes is something like a track bar, control arm, or something else that isn't torqued exactly to the right spec that can make a noise like this.
I am however betting it involves something not being tightened correctly, especially since it's not stock.