A lot will depend on the year(s) you're working with. The typical '60's-70's B-body upper ball joint is a K772 or for the adjustable one, a K720A. These are the same numbers for the C-bodies up to '73 and the '73-6 A-bodies. The '72 and earkier A's use the K704 or K706 (adjustable). The '74-8 C-body uses a K778. These numbers are out of a '76 Moog catalog so there may be some supercessions or number changes since then.