Spray the top of the steering box with a little brake cleaner to clean the dirt off.
Work on the truck from underneath. Key turned on one notch to unlock the steering wheel, but truck not running. Wheels on ground.
Use a 16 mm wrench and a 4.5 mm hex wrench (I think, if not 4.5, then 5.0)
Insert the hex wrench into the center of the adjusting screw and point it towards the front of the truck.
Hold the hex wrench and loosen the locknut.
Have wife, g/f. wiggle steering wheel, (this may result in a visual bonus) or else get up and down a lot.
Tighten hex wrench about 1/4 turn at a time to take up the play. I turned mine about 3/4 turn to take up 2 inches of play in the wheel.
Hold hex wrench and tighten locknut.
You're done, take it for a test drive.
If you go too tight you will feel it "binding" when you turn. If its too tight it will cause premature wear on the steering box.
If you wrote this you left it laying on the floor at another site. I just picked it up for you.