I did mine (47 AD 1.5 ton) a few years back. Both balls replaced and overhauled the drag link. I kept all the small parts I replaced on the truck as they are very handy for reference and take up litte space. So:
The balls are 1 inch. On the steering arm off the spindle, mine looks to be peened over, but may be welded, I cant remember. looks peened. Welding steering parts is illegal here. The old part looks like I cut it off on the ball side close to the arm then punched it through. On the Pitman arm off the steering box I have used a bolt in one.
If you search drag link on the Filling Station site, all the balls look applicable. Also get the overhaul kit FS-148 as it fits all cars and trucks 1932-1959, that shows sizes were very common.
These guys also list the parts
http://www.truckandcarshop.com/trucks47_59/t47_117.htmlYou need to overhaul the drag link.
From some radiator hose that was a perfect fit (metric size I think, not sure) I made sleeve covers for each end of the drag link that will help keep the dirt and water out and the grease in.
