Yamaha - Gear 2 Lower Unit Drivetrain Component 6J8-45571-00-00. Overview. When you start hearing noise or feeling rough engagement in the lower unit, gears are usually where the problem begins. This gear plays a direct role in how power is transferred and how smoothly the motor shifts under load. I've seen worn gears cause all kinds of issues that disappear once replaced. It's one of those internal parts that keeps everything running clean and predictable when it's in good shape.. Key Features. Smooth Gear Engagement - Designed for clean interaction with mating gears inside the lower unit.. High-Strength Construction - Built to handle continuous load and torque from engine output.. Precision Machining - Ensures proper alignment and reduced wear during operation.. Factory-Spec Fitment - Matches Yamaha drivetrain systems for accurate installation.. Wear-Resistant Design - Engineered to maintain performance over extended use.. Engine & Boat Compatibility. Designed for Yamaha outboard eng