1pcs 1 7/8" MainShaft Sprocket Tool. 1 7/8" Main Shaft Sprocket Tool for Twin Cam 1936-2006 for Big Twins 1999-2006. For Big Twins 1999-2006. For Twin Cam 1936-2006. It focuses on researching and developing various performance products, such as, high-performance racing car’s connecting rod, crankshaft, piston, suspension and air spring.