Odd steering problem on k10

[landy]

All, I've got an unusual steering problem on a '71 k10 that I recently bought.

It's got power steering and original open knuckle front diff. When turning the steering wheel (either to left or right) at 90 to 180 degrees from center, I feel a noticeable stiffness. Before and after that position, steering turns normally.

With both front wheels off the ground, the stiffness is barely noticeable when turning the steering wheel. With the wheels off the ground, they both turn nicely with no play when moving the tires in and out.

Truck drives very nice down the highway with no wandering or vibration or shimmies.

The p.o. had had the steering wheel off to replace the turn signal switch. I recall that there's a bearing in the column, but I can't imagine a bad bearing here would cause this.

Failing steering box or any other thoughts?