I have a '96 Safari and my steering box has no provision for adjusment. Mine wandered like there was play in the box. What I found was the two bolts in the u-joints above the box were loose. Tightned them up and it make a HUGE difference in my coach.
Put some vice grips on the steering shaft above the u-joints and turn it and see if you have any slack there.
'96 Safari 3540, 300 CAT, Fulltimer since 12/00