Yamaha - Lower unit assy - 6KB-45300-00-8DYamaha Lower Unit Assembly Outboard Drivetrain 6KB 45300 00 8D Overview You can usually feel when a lower unit isnt rightextra noise, rough shifting, or it just doesnt push the boat like it should. This is the kind of replacement that brings everything back to smooth, dependable operation. Once its installed, you get that clean engagement and steady power transfer you expect from a Yamaha. Its a solid fix that lets you run without second guessing