Yamaha Lower Unit Assy - 6FM-45300-20-8D. The Yamaha Lower Unit Assy - 6FM-45300-20-8D is engineered to enhance the performance and reliability of your Yamaha outboard motor. This lower unit assembly ensures a precise fit and optimal operation, boosting the overall efficiency of your marine engine. Constructed with premium materials, it is designed to withstand the harshest marine environments, providing exceptional durability and dependable performance.. Experience smooth and efficient power transmission with the Yamaha Lower Unit Assy - 6FM-45300-20-8D, which minimizes drag and maximizes thrust for improved fuel economy and a more enjoyable boating experience. Trust in Yamaha's commitment to quality and innovation with this lower unit assembly, ensuring your boat performs at its best across various conditions, delivering a reliable and enjoyable experience on the water.. This product has been superseded by: 6FM-45300-22-8D. 6FM-45300-20-8D - LOWER UNIT ASSY