common leakage underneath though
is your steering box leaking? i replaced my steering box because of a steering input shaft, but never had any steering problems with my old box... maybe yours is completely shot?

as for checking the swivel pin preload of panhard rod bushings. Les had me have someone turn the steering back and forth with the tires on the ground and engine off... looking for excessive movement in the panhard rod bushings and ball joints.

swivel pin preload requires a little more... check joey4420's link above about preload check and adjustment... i just did this and my shakes are gone