Just bought a 98 blazer with 117,000 miles. Noticed that there was some slop in the steering and that it had a tendency to drift back and forth across the road. I have replaced all the ball joints and the pitman arm. The front end is really tight now but I still have some of the slop. I have nailed it down to the steering gear box. With the wheels on the ground you can move the steering wheel in each direction about a 1/2 "before the tires move. There appears to be an adjustment nut of sorts sticking out of the top of the gear box. Is this something I can adjust to take slop out and if so how do you adjust it?

See my post at the top of the forum (Facts about steering slop) It's more likely the rag joint on your intermediate shaft.

Did you have the front end aligned since the front end work was done? Toe adjustment can cause wander.