Get a German rubber/rag joint ONLY! DO NOT GET ANY URETHANE! If it's cracked, replace it.
I cannot stress this enough, your life depends on it.
Also tighten the pitman arm nut, a lot of times this nut looks tight but if you really crank on it, you'll get 1/16th of a turn. This can and does make a difference, and this fix has worked for many others.
I've never seen a steering box with only one adjustment, so I don't know what to tell you there.
Also tighten the steering box attachment bolts.