Yamaha - Lower Unit Assembly 6G1-45300-12-EK. Overview. The Yamaha Lower Unit Assembly 6G1-45300-12-EK is what keeps your motor actually pushing water the way it should. When a lower unit starts going bad, you'll notice it quick-noise, rough shifting, or loss of power at the prop. Instead of chasing multiple internal issues, swapping the full unit is usually the cleanest fix. This setup gives you a solid, reliable base again so you can run without second-guessing what's happening below the waterline.. Key Features. • Complete Drivetrain Assembly - Replaces internal gears and components in one unit for reliable performance.. • OEM Fit Precision - Built to Yamaha specifications for direct fit and proper alignment.. • Smooth Gear Operation - Supports consistent shifting and dependable performance under load.. • Corrosion-Resistant Construction - Designed to handle saltwater use and harsh marine environments.. Compatibility. Compatible with select Yamaha outboard engines using this lower u