Yamaha - Lower Unit Assembly Outboard Drivetrain 6L2-45300-04-8D. Overview. You can usually tell when a lower unit is starting to go-shifting gets rough, noise creeps in, and the motor just doesn't feel right under load. This is the kind of replacement that brings everything back to smooth, reliable operation. It lines up the way it should, runs quiet, and gives you that solid feel when you drop it into gear. Once it's on, it's the kind of part you don't have to think about again.. Key Features. Smooth Power Transfer - Delivers steady engine output to the propeller with minimal vibration.. Corrosion-Resistant Housing - Built to handle harsh marine environments, including saltwater use.. Factory-Spec Fitment - Designed for proper alignment and seamless installation on Yamaha outboards.. Durable Internal Gearing - Supports long-term reliability under regular use and load.. Complete Assembly Unit - Pre-assembled design reduces downtime and simplifies replacement.. Engine & Boat Compatibil