I would let the truck sit on the ground, get under it, and have a buddy get in and crank that wheel back and forth, you should be able to spot where the slop is. Also, don't overlook the steering shaft itself, it is often overlooked, since it's on the input side of the system, any play here translates to very loose steering. Grab a couple pairs of vice grips and grab the upper and lower shaft sections, and wiggle in opposite directions, if you can move them at all, replace the shaft.
I'm not arguing the fact that there are many other steering components that can cause slop in the steering system BUT for 73k5blazer to say that "It's a pre-load adjustment only and has 0 control over introducing or removing any "play" in the system" is highly mistaken.
This friend of his that is "an Engineer at Delphi and know the people who build these boxes in Saginaw for a living" should see this post and set him straight.
I'm not trying to mislead anybody. I know how these boxes are assembled and I know my friends
full position on this, as he's rendered it many times to me and others. There are alot of builders who think that nut on the top is something to play with to remove slop too, that doesn't make them right. I've watched my buddies reaction to a mag writeup years ago on how to rebuild these boxes where they said to just crank that thing down by some human feel and then back it off a touch. Just because some person the mag writer found who builds his boxes that way wrote it, doesn't make it right.
That shaft should be touching the rack nut as soon as you torque down the 4 main cap bolts, that's one of the reasons they want a metal gasket on it because the tolerance is tight and a regular gasket could tighten too much or too little and the teeth wouldn't be meshing properly and then you may have the scenario you describe. The adjustment just pushes harder down and if you go too much, since the teeth are already meshing, it'll push it off kilter because of the shaft teeth taper and thats where some trouble can be had.
You can't back it off enough to cause the teeth to become unmeshed and introduce slop (I think this is the main point of contention), if it's able to do that, then you have one massively worn shaft or rack, a point which I've only ever seen reached when something else in the box already broke or there are alot of hard miles on the box. I guess from that perspective, at that point, there may be chance to crank it down and remove some slop, but not recommended, if it's worn that much, it should be overhauled, as he did.
If one really wants to adjust it, heres how to do it right (taken from the 1978 GM Unit Overhaul Manual).
(Click on it for full size)
