[Bob Bidonde]

Check all of the front suspension including:
> Loose / cracked front frame cross-member;
> Broken / worn-out front spring;
> Broken front spring attachments to the cross-member;
> Play in king pins;
> Loose wheel bearings;
> Bent front wheel rims;
> Wheels out of balance;
> Loose / out of round drag link & tie rod ball joints;
> Loose steering connection to the frame.

I doubt that the front radius rod ball joint can cause the wheels to shimmy.