the bolt holes should be the same size , same part number--- can't remember the size off hand but do remember opening mine up by 1/64th inch when I was young and dafter than I am now., but if you have a very large bolt hole that bolt is for the drain pipe on B series engines , mmmmm the holes may be 1/32nd inch----- I think the outlet hole into the rockers is the same as well or surely it would be a different part number--- mmmmmmm again they are a different bolt from years 54 to 63 , I bet someone will have the information somewhere but inlet and exhaust banjo bolts still have the same part number as each other