I kind of wonder on mine.. It "feels" like about one to two inches of steering play when you're driving, but when I have it running and watch the front rim, it actually starts responding to input in under an inch (somewhere between 1/4-1/2 inches). I'm sure there's a bit (or more) of sidewall deflection involved. It feels pretty funky on backcountry hilly roads, and takes concentration, for sure!
Tyler, when you're talking about XJ shaft, do you mean the column, or the link between the pitman and idler on XJ's? I wouldn't have thought that (the later item) stout enough for these trucks..it was always a questionable item to look at with XJ death wobble problems.
EDITED - Never-mind Tyler, I googled it