OT FYI either pump will fit either timing cover, mainly done to use a pump with its nipple on the same side as a different radiator then remark the dampener. Actually You can keep the hose and t cover/dampener timing marks on the same side you just have to aim the light just right but it is easier to just remark the dampener on the other side but there is a early 273 V8 bolt on timing tab out there that puts the marks on the pass side (like the cast in marks on the early t cover) if using the early pump and the later t cover. EDIT The early cast pump is much thinner which will require a different pulley