Yamaha - Lower Unit Assembly Gearcase Component 6P2-45300-30-8D. Overview. When a lower unit starts wearing out, you feel it right away-rough shifting, noise, or just a loss of that clean push through the water. I've swapped out plenty of these on F250 setups, and a fresh assembly always brings the motor back to life. Everything runs smoother, quieter, and more predictable under load. It's one of those upgrades that makes the whole boat feel right again.. Key Features. • Complete Gearcase Assembly - Provides a full replacement with matched internal components.• Smooth Power Transfer - Delivers consistent output to the propeller for reliable performance.• OEM Precision Fit - Built to Yamaha specifications for proper alignment and installation.• Corrosion-Resistant Build - Designed to withstand harsh freshwater and saltwater use.. Engine & Boat Compatibility. Designed for Yamaha F series outboard engines, including high-horsepower four stroke models. Commonly used across a range of Yamah