Take a look at the photo above. That small area in color shows the steering box. On Bob's '62 Galaxie, the preload adjustment screw is on the top of the box, but on the '60 F100, that bolt on top is a filler cap for gear oil. When we took that cap off, we found that there wasn't any oil in there, so we filled it up.
The adjustment screw was on the side of the box toward the engine, in a really tight spot. We were able to get to it, though, with a 3/4-inch box wrench (to loosen the locknut) and an offset screwdriver (to turn the adjustment screw.) It was a pain in the ass, but we managed to take quite a bit of play out of the steering. That was the good news. The bad news was that the gears in the steering box are showing a lot of wear. I'll be able to keep adjusting them for awhile, but sooner or later I'm going to need to put in a new or rebuilt box.
While I was under the truck, I inspected the speedometer gear in the transmission. Good news and bad there, too. The gear is brand new and in perfect condition, but that just means that the problem with the speedometer is probably in the instrument cluster. There's more work to be done there.
And the gas gauge isn't working because there's no voltage going to the sending unit in the tank. The wiring under the dash is a bird's nest of black wires, all bundled tightly up with plastic cable ties. Sometime this week I'm going to try to crawl under there, cut the cable ties, and trace out the wires to see exactly why some electrical things are working and some aren't.