About the only other source for that much free play would be in the spool valve which directs the steering pump boost pressure to the proper direction as the wheel is turned. If that's the case, the box is deadly dangerous, since the input shaft could disconnect internally and leave you with no steering whatsoever, without warning. I've seen that happen on race cars where a power steering box was used without the power assist, to take advantage of the quicker ratio it provides.
Jerry
