Yamaha Lower Unit Assy - 6G5-45300-18-8D. The Yamaha Lower Unit Assy - 6G5-45300-18-8D is meticulously engineered to provide superior performance and reliability for your Yamaha outboard motor. This lower unit assembly guarantees a precise fit and optimal functionality, significantly enhancing the overall efficiency of your marine engine. Constructed from high-quality materials, it is built to withstand harsh marine conditions, ensuring long-lasting durability and consistent performance.. Experience smooth and efficient power transmission with the Yamaha Lower Unit Assy - 6G5-45300-18-8D, which minimizes drag and maximizes thrust. This leads to improved fuel economy and a smoother ride on the water. Trust in Yamaha's dedication to quality and innovation with this lower unit assembly, ensuring your boat operates at its peak in all conditions, delivering a reliable and enjoyable boating experience.. This product has been superseded by: 6G5-45300-1B-8D. 6G5-45300-18-8D - LOWER UNIT ASSY