Yamaha Lower Unit Assembly - 6H3-45300-E8-8DYamaha Lower Unit Assembly Gearcase & Propulsion System 6H3 45300 E8 8D Overview When a lower unit is solid, you dont think about ityou just run the boat and trust its going to do its job. But when it starts slipping, grinding, or making noise, its usually time to stop patching things and replace it outright. Ive swapped enough of these to know a complete assembly saves time and headaches compared to chasing internal damage. Once its on and set up