I also check those boxes for end play at the input shaft and sector shaft..If you can push up and down on the pitman arm and see that there is up and down motion, the sector shaft needs adjustment. In and out play at the input shaft on a manual box can be adjusted at the threaded bearing housing and locknut on the end of the case.
There is an adjustment procedure, do not just tighten everything up, as it will do more harm than good.
Here is the basic procedure, I copied it from an earlier thread.
The basic procedure for later boxes, (525's, vegas, etc), involves dropping the pitman arm, loosining the adjuster screw at the top of the sector shaft, tightining the bearing housing/nut until the steering input shaft has all the play taken out, and there is a 2 to 4 inch pound drag on the bearings.
Then re tighten the sector shaft (pitman arm shaft), adjuster until there is an additional 2-4 inch pound drag on the box as a whole. You will have some problem making that procedure to work as your box has (presumably) alot of wear. and it is very hard to find an in-lbs torque meter with a 0-30inch pounds range.
In your case, I would try to just snug up the input shaft until just before it starts to get clunky, then adjusting the sector shaft intil you get the play out. Do this sector adjustment with the box centered only, you can't do anything about the looseness off center beyond what you will get from the adjustment at center position. It is because of the way the gears are ground with a "hard spot" at center.
You can do all of this in the car if you have access to the screws etc ,but it is much easier to do it on the bench, once you know what you have to do. If it feels good on the bench, chances are, it will feel good in the car.
You won't get all the play out, because as F&J already said, the bushings are probably worn, also the balls and ball channels are worn as well.
Check your rod ends and kingpins as well.
hope this helps, mikey