Check for play in the tie rod ends and the drag link ends. They are adjustable. Lucas S Drake may not have known the correct procedure to adjust them. The instructions are spelled out nicely in the Chevrolet Truck Repair manual. You need one of those if you haven't bought one yet.
I would not touch the obviously recently rebuilt steering box whatsoever yet. It is not likely the problem, but the other steering components are easier to adjust and more likely the problem.
