Norton crankcase cylinder stud 3/8 inch, to hold cylinder barrel to crankcase on all Norton twins pre 750. 7 reqd pre 1957, 6 reqd 1957+. 3/8 inch Whitworth X 3/8 inch BSC 26tpi Original part number D12/2(L);T2018; 067871 - crankcase cylinder base stud 3/8 inch dia