The Sierra 18-3781 Prop Nut Kit is interchangeable with the following: GLM 21261, Mallory 9-73991, Yamaha 6H1-W4599-00-00. Each Sierra product meets or exceeds the original equipment part it replaces. Contains: 18-2380 Cotter Pin, 18-4274 Prop Spacer, 18-3732 Prop Nut.