Upper or lower ball joints? Lower ball joints are "not service-able" and come on new lower control arms; MOOG K8123. Uppers are replace-able; MOOG K8036 for 4-holes and MOOG K8142 for 3-holes. You ofcourse do not have to buy MOOG parts, but I personally recommend them.
If the arms have not been changed...3 rivit. Its easy enough to find out. Jack a front wheel off the ground...remove it and count the rivet heads on the upper arm at the joint.