Yamaha - Gear 2 (21t) - 6CB-45571-00-00Yamaha Gear 2 (21 Tooth) Lower Unit Gear Component 6CB 45571 00 00 Overview This is one of those parts you dont think aboutuntil the lower unit starts acting up. The Yamaha Gear 2 (21 Tooth) sits deep inside the gearcase, handling load transfer and helping keep everything turning smoothly under power. When it wears, youll hear it before you see itgrinding, slipping, or just not feeling right under throttle. Swapping it out restores that solid,