Yamaha Lower Unit Assembly - 6H3-45300-17-8DYamaha Lower Unit Assembly Gearcase & Propulsion System 6H3 45300 17 8D Overview When a lower unit goes, you dont always get much warningand it usually happens at the worst time. Ive replaced enough of these to know that a complete assembly saves a lot of guesswork compared to piecing things back together. Its the backbone of how your motor puts power into the water, so everything has to be right. Swapping in a solid unit like this gets you back to