Guys, I'm no steering expert but here are my thoughts. I think the boxes originally came with a type of gear oil (?) and owners converted them to grease. In fact, my box has grease. If there is oil in your box, may need to drain it before adding grease. I had lots of slop in my box due to worn parts all over the front suspension including the box. You will see what looks like a screw on top with a jamb nut. Loosen the nut and turn the screw about 1/4 turn and recheck tightness of steering. If the steering is still loose, then turn screw another 1/4" turn and check...you get the picture. The main thing is not to turn that screw to far.....which is what most people do! It can really make a huge difference. I went one further because I had to replace the front seal in my steering box due to leaking grease. Therefore, I was able to also increase load on front bearings of box where steering shaft enters the box. Also, check your ragjoint. Mine was old, soaked in oil and grease and had metal sticking out of it. If you have the original ragjoint, it's probably due for replacement. I used the $12.00 aftermarket replacement. I would rather of used a GM stock replacement now that I've used this cheap part.
After the ragjoint and steering box, the idler arm is also a wear item that you may want to check. Should not have more than about 1/4" movement. I think I need to replace mine in the near future.
Jim