Yamaha - Lower Unit Assembly Gearcase Component 6CE-45300-A3-8D. Overview. The Yamaha Lower Unit Assembly 6CE-45300-A3-8D is built to deliver smooth, reliable power transfer from your engine to the water. This is the part that handles propulsion, so when it starts to wear, you'll notice it immediately-vibration, noise, or loss of performance. Designed to Yamaha's exact standards, this assembly restores proper operation and ensures your outboard runs efficiently in both freshwater and saltwater conditions.. Key Features. • Efficient Power Transfer - Delivers smooth propulsion from engine to propeller.. • OEM Fit Precision - Engineered to Yamaha specifications for seamless installation and alignment.. • Complete Gearcase Assembly - Pre-assembled for dependable performance and easier replacement.. • Corrosion-Resistant Construction - Built to withstand harsh marine environments.. Engine & Boat Compatibility. • Compatible with select Yamaha outboard models(Verify exact model compatibility