Yamaha Lower Unit Assembly - F250 - 6P2-45300-20-8D - See Description for Applicable ModelsYamaha Lower Unit Assembly Gearcase Component 6P2 45300 20 8D Overview On these F250 motors, the lower unit is what you feel every time you shift and throttle up. Ive seen boats lose efficiency and smoothness just from wear down there, even when the powerhead was still strong. Swapping in a complete assembly like this brings everything back to tight, quiet operation. Its the kind of fix that makes the boat feel solid again the moment you put it in