Yamaha - Gear 1 Assembly Drivetrain Component 6K5-45560-00-00. Overview. The Yamaha Gear 1 Assembly 6K5-45560-00-00 is one of those internal parts you rely on every time you put the boat in gear. When everything's working right, you don't think about it-but when it's worn or damaged, you'll hear it and feel it immediately. This assembly handles load transfer inside the lower unit, so it needs to stay tight and properly aligned. If you're rebuilding or fixing gear issues, this is a key piece to get things running smooth again.. Key Features. • Integrated Gear Assembly - Combines critical components for consistent internal power transfer.. • Smooth Engagement Operation - Helps maintain clean gear movement and reduce drivetrain noise.. • Precision Machined Fit - Designed for proper alignment within the lower unit housing.. • High-Load Durability - Built to handle torque and stress from continuous operation.. Compatibility. Compatible with select Yamaha outboard engines using this Gear 1 a