Yamaha - Lower unit assy - 6EK-45300-03-8DYamaha Lower Unit Assembly Gearcase & Propulsion System 6EK 45300 03 8D Overview You can tell right away when a lower unit isnt rightnoise, vibration, or just not getting the push youre used to. Ive replaced enough of these to know a complete assembly saves a lot of time and guesswork compared to rebuilding one piece at a time. This is the part that takes all the load under the water, so it needs to be solid every time you throttle up. Once its bolted