Yamaha - Propeller Shaft Lower Unit Drivetrain 6AX-45611-00-00. Overview. This is the backbone of your lower unit-the part that actually spins the prop and pushes you through the water. When it's straight and solid, everything feels smooth and predictable. But once a shaft gets bent or worn, you'll notice vibration, noise, or even seal issues pretty quick. Yamaha builds these to take real-world hits and torque, whether you're cruising long runs or working in rough conditions.. Key Features. Direct Power Transfer - Carries engine torque straight to the propeller for consistent thrust.. Precision Machined Fit - Built to exact tolerances for proper alignment inside the lower unit.. High-Strength Construction - Designed to handle heavy loads, impacts, and continuous use.. Seal Surface Integrity - Smooth surfaces help protect seals and reduce the risk of leaks.. Engine & Boat Compatibility. Designed for Yamaha outboard lower units using this propeller shaft configuration. Commonly found in