early A-body Power steering
Is it possible that your input shaft preload adjustment recommendation applies only to manual steering boxes?
Yes, that is the case.
just "tighten the big screw until you can feel it, then back off a little,"?
(1) Disconnect center link from steering gear arm.
(2) Start engine and run at idle speed.
(3) Turn steering wheel gently from one stop to the
other, counting number of turns. Then turn wheel back
exactly halfway, to center position.
(4) Loosen adjusting screw until backlash is evident in
steering gear arm. Feel backlash by holding end of
steering gear arm between thumb and forefinger with a light grip. Tighten adjusting screw until backlash just
disappears. Tighten to 3/8 to 1/2 turn from this position and tighten lock nut to 50 foot-pounds to maintain this setting.
Just like it says in the FSM.