Yamaha - Gear 2 Assembly Drivetrain Component 6K1-45570-20-00. Overview. The Yamaha Gear 2 Assembly 6K1-45570-20-00 is one of those internal parts that keeps your lower unit running quiet and smooth when everything's right. Once gears start wearing out, you'll hear it first-then feel it under load. This assembly handles a big part of the power transfer inside the gearcase, so it needs to stay tight and properly matched. If you're already opening up the lower unit, replacing the full assembly saves you from chasing problems later.. Key Features. • Complete Gear Assembly - Includes matched components for consistent internal drivetrain operation.. • Smooth Power Transfer - Helps maintain quiet and efficient movement through the gearcase.. • Precision Fit Components - Designed to align correctly within Yamaha lower unit housings.. • High-Load Durability - Built to handle torque, stress, and continuous use on the water.. Compatibility. Compatible with select Yamaha outboard engines using th