Yamaha - Gear 1 (1.841 Ratio) Internal Drivetrain Component 6T5-45881-20-00. Overview. The Yamaha Gear 1 (1.841 Ratio) 6T5-45881-20-00 is one of those internal parts you don't see, but you'll definitely notice when it starts going bad. When a gear wears down or gets damaged, it shows up fast-noise, rough operation, or inconsistent power transfer. This gear plays a key role in how power moves through the system, so it needs to stay precise and properly meshed. If you're already inside the lower unit or engine, this is one of those parts worth replacing while you're in there.. Key Features. • Reliable Power Transfer - Moves rotational force between components for smooth and consistent operation.. • OEM Fit Precision - Built to Yamaha specifications for proper gear meshing and alignment.. • Optimized Gear Ratio - 1.841 ratio supports a balanced mix of power and efficiency.. • Durable Load Handling - Designed to withstand continuous torque and marine operating conditions.. Boat Compatibili