Steering issues
As far as the steering gearbox goes, there are two gears in there. One is a worm gear that is attached near the bottom end of your steering shaft. The other is a gear section (sector gear) that fits into the teeth on the worm gear. The gears are designed so that with the steering centered, the worm and sector gears mesh together the closest. As you turn either way from center, the gears are designed so that their teeth gradually fit together more loosely. This is all assuming you have either a new gearbox, new gears, or gears with only a small amount of wear.
As the gears wear, they are designed so that the sector gear can be pushed closer to the worm gear by adjusting a threaded stud (steering box adjuster) and then locking it in place with a lock nut. The steering gear adjuster and lock nut are on the inboard side of the steering box (see the photos on Earl's World). At some point, the gears either have large pits and gouges or are just so worn down that adjusting them closer together does no good.
To check your box, jack up the front so both wheels are off the ground. Center the steering and loosen the steering box adjuster lock nut. Slowly tighten the adjuster stud using a slotted screwdriver. As you tighten the adjuster, the "slop" in the steering wheel should get smaller. At some point, you should find that the steering feels stiff as you cross the center position. That means you've pushed the sector gear too close to the worm gear and they are binding at the center steering point. Back the adjuster off just a little until the steering wheel turns freely through the center point. Finally, tighten the lock nut on the adjuster. Sometimes as you tighten the lock nut you move the adjuster stud a little. You may need to tweak it a second time to get it right. The adjuster isn't like doing brain surgery - if you get it close you'll be fine.
If your gearbox is worn out, no amount of adjustment will fix the steering. You'll either need to get a rebuilt unit or a rebuild kit to do it yourself.
Keep in mind that there are at least half a dozen other things that can cause loose steering. Front leaf spring bushings and pins, king pins and bushings, tie rod ends, drag link innards, even worn or badly adjusted wheel bearings. While you have the truck jacked up (and on jack stands - safety first!), wiggle things around and see if there is any play in the front end components.




