Yamaha Lower Unit Assembly - 6E5-45300-18-8DYamaha Lower Unit Assembly Complete Gearcase & Drive System 6E5 45300 18 8D Overview When a lower unit starts making noise or loses efficiency, its usually not worth piecing it togetheryou swap the whole assembly and move on. Ive installed plenty of these, and a complete unit like this saves time and guesswork. Everything is already set up to work together, so you get smooth power transfer right away. Bolt it on, fill it, and youre back on the water