Share your steering box wisdom.

[shp4man]

Ok, so the old 1965 C10's manual steering box has about 7 inches of play that won't adjust out. Oddly, the rest of the front end parts are pretty decent.
The box has a lash adjuster on it, which I tried 1/4 turn at at time, and it worked for about 20 miles, but now it looks like the shaft that the pitman are is attached to is actually moving downward, coming out the bottom in other words. WTF?
So, rebuild kit? Reman box?
Not super interested in a power steering setup. Thanks in advance.