Cylinder head nut (sleeve nut) Norton OHV alloy head, each, stainless steel, 3-1/8in (79mm) under the head, through drilled, overall length 6-5/16in. All the OHV sleeve nust have the same thread. Use with stud 9136; A2/155 Original parts numbers: C126; D3T/156 - Cylinder head holding down stud nut