[vatdevil]

If you switch to Mustang II spindles, the bottom ball joint connection is a bit larger initial diameter(.69 vs .72). This is because the SPF spindle is designed to use upper style ball joints (smaller) for the lower ball joint. You will want to insure the lower ball joint seats properly and doesn't bottom out. This also causes a slight change in front geometry, as the lower control arm will be slightly higher, how much of a change I don't know. If you use the Wildwood spindle, the upper ball joint height is raised 1/2 inch. This is to improve the original Mustang II geometry. What it does to SPF geometry I don't know.