If the lower ball joints are still nice and tight on your car, they can be used by drilling the mounting bolt holes larger from 1/2 inch to 9/16 inch, or you buy new disc brake lower ball joints that are 9/16 inch that attach to the spindle.
The difference in ball joints are DRUM brake ball joints mount to the spindle with 1/2 inch bolts, and DISC brake ball joints mount to the spindle with 9/16 inch bolts.
