Direct replacement for OEM-style rocker shaft. As used with KD forged rockers, Roll-tipped rockers, etc. (but not needle roller types). Far superior to the stock item! Rocker shaft wear is super easy to detect! With the valve cover removed, push on each of the rockers until you find one that is not quite in contact with a valve stem so that it can be slid sideways exposing the rocker shaft. Now the only difficult part is the majority of the wear takes place on the bottom of the shaft! This is after all where the load is absorbed. Our special "heavy duty" shaft not only is made of a better grade of metal and has a super finish but it is also has an increased wall thickness. This means that although the shaft is totally interchangeable with the original stock version, it is a significant upgrade! Also fits the Sprite , MG Midget , and Morris Minor.