[UPOVR]

Is the pump making any noise when you attempt to turn it (growning)? Have you run it low on fluid ? Maybe air got into the system. There's a bleeder screw on the box you can loosen to bleed the box/system. cover your ratchet/ wrench with a rag or you'll be covered with ATF. Also check the Metal U-Joint on the steering shaft. These can where out too. The only other thing I can think of besides the obvious ( Steering box/ PSPump) is the bearings located in the knuckles top/ bottom. I ahd a friend who had these go out from mud/ water seeping in. caused the truck to feel like it was oversteering and pretty scary on the highway. hopes this helps.

 

[UPOVR]

you can adjust out the steering stops to keep the tires from rubbing the radius arms. there are bolts located on the knuckles and they contact the flange (steering stop) that holds the knuckle onto the axle housing. when at full lock this contact limits your turning radius/ tire rubbage (is that a word?).