You can also make an adjustment at the spanner type nut where the steering shaft goes in. When I replaced my input shaft seals I tightened that up about 1/8th turn.
I can actually let go of the wheel on the highway at speed and the truck tracks straight. None of that sawing the wheel side to side anymore.
I'm no steering box expert but I did do some searching and reading on it because I was replacing the input seals and had to take that apart anyway. There is a proper way to adjust this, something about measuring the turning torque of the input shaft. Needless to say I didn't do that, just made my adjustment with an edumacated guess.
I'm thinking a lot of the steering slop comes from this adjustment. Basically, when I put it back together, I thought I had it in the right spot via my markings I made before removal. So, when I turned the steering wheel, it would go about a 1/4 turn before any movement of the pitman arm. As I turned the wheel (actually I was grabbing the steering shaft with my hand and turning that) I was watching the input shaft slide in/out of the box before hitting the stops and effecting the pitman. I had another turn or two on the spanner nut to go. I ended up locking it down 1/8th turn past my original markings and I feel it steers like it should have from the factory. Been a few months now. So far, so good.
So, with heed, try making that adjustment. If you adjust too far it can ruin the box. Just remove the big stamped steel lock nut, and that will reveal the spanner nut (round and flat with 2 holes in it). I didn't have the proper tool for it but I did have a brass punch and a hammer, and that seemed to work fine.