Sierra International 18-3782 Prop Nut Kit Sierra Prop Nut Kit Contains: 18-3726 Prop Nut, 18-3735 Cotter Pin, 18-4274 Prop Spacer Sierra part number: 18-3782 Interchangeable with the following: GLM 21251, Mallory 9-73992, Yamaha 6G5-W4599-00-00