This OEM lower timing gear cover (CX2430) is designed specifically for the "J" series Magneto's because the timing gear in the model "J" is located in this lower cover. A new bushing for the timing gears comes already installed in the cover. Unlike the "X" model Mag, the timing gear was moved to the breaker plate making the "X" lower cover completely different. Always inspect the lower cover for cracks around the bushing area or mounting screw area.  Replace if cracks are found. It is most important that this lower cover be strong and not move due to cracks for proper timing gear mesh.