Yamaha Lower Unit Assy - 6EM-45300-13-8D. Upgrade your Yamaha outboard motor with the Yamaha Lower Unit Assy - 6EM-45300-13-8D. This high-quality lower unit assembly is designed to deliver exceptional durability and efficiency, ensuring smooth and reliable operation in various marine environments. Precision-engineered for optimal power transfer and gear ratio, it enhances your boating experience with robust performance. Built from premium materials, this assembly is made to withstand the harshest marine conditions, providing long-lasting functionality.. The Yamaha Lower Unit Assy - 6EM-45300-13-8D is compatible with a broad range of Yamaha outboard models, offering versatility and ease of installation. Its durable construction guarantees consistent performance, making it an essential component for any serious boater. Rely on Yamaha's renowned engineering and commitment to quality with this superior lower unit assembly, designed to enhance the reliability and performance of your outboar