The shimmy most likely exposed a warn tie rod end or Pittman arm. Possibly a worn spring bushing. Unless you put a lot of pressure on the screw you won't break a bearing. My money is on a worn part. You can readjust the box and look at one part at a time. I like to get a helper to sit in the truck. They wiggle the wheel while I look at each part to see where it gets sloppy. I do this with the truck on the ground. It will expose the worn part rather quickly. Helper can watch for the steering wheel moving in and out of the column. If it all looks good then check those king pins. You will need to lift it for that. Don't forget wheel bearings as well. The shimmy is putting more force on those parts than you can.
