Ball joints
Jack the truck up and put a bar under the tire and lift up and down similar to checking bearings. Watch the ball joints while doing this and see if there is any play. Usually it helps to have a second set of hands to help. I usually find the top ball joints go bad before the bottoms. If any of them are bad, do yourself a favor and just replace them all.
You may also want to take a look at your sway bar link bushings. Mine were bad and caused a popping noise when I hit bumps.
Long winded, but hope some of that helped.:thumb: