Yamaha - Lower Unit Assembly F150 Complete Drivetrain Assembly 6HP-45300-00-8D. Overview. The Yamaha Lower Unit Assembly F150 6HP-45300-00-8D is what takes everything your engine produces and turns it into real movement in the water. When a lower unit starts wearing out, you'll feel it fast-vibration, noise, or loss of performance when you throttle up. Instead of chasing internal gear issues, swapping the full assembly is usually the most reliable way to get things back to normal. It gives you a solid, ready-to-run setup so you can focus on the ride, not the repair.. Key Features. • Complete Drivetrain Assembly - Replaces internal gears and components in one unit for dependable performance.. • OEM Fit Precision - Built to Yamaha specifications for proper alignment and straightforward installation.. • Smooth Power Transfer - Supports efficient thrust and consistent operation under load.. • Corrosion-Resistant Construction - Designed to handle saltwater exposure and harsh marine environm