I've gone through and replaced all the parts on my K25 (drag link, tie rods, ball joints, rag joint, etc.), and then adjusted the steering box.
To properly adjust the steering box you need to:
- disconnect the tie rods from the steering arm so it moves freely.
- Ensure the steering wheel is centered by moving it through the full range. In my truck there was a flat section of the steering shaft that faced up when it was centered.
- Put an inch lbs torque wrench on the nut in the middle of the steering wheel.
- Loosen the lock nut with a wrench, and tighten down the center screw nut with an allen wrench until the torque needed to move the steering wheel is within specs.
- IIRC the torque was something like 8-12 inch lbs, but I would have to look it up again.
This adjustment takes out the free play in the box, but you don't want to get carried away because it will make the steering bind at certain points. Many guys just crank it down a 1/2 turn at a time (without measuring torque) and see how it feels - there is some risk that it may bind.
On newer trucks (79+?) you can also replace the rag joint with a steering shaft and universal joint from a jeep. However, the splines on older trucks like my '75 are different and you can't use the jeep shaft.
Bruce