Yamaha - Gear 1 Assembly Lower Unit Drivetrain 6E0-45560-00-00. Overview. When you're dealing with lower unit issues, gears are usually where things get serious fast. I've pulled apart enough units to know that once a gear starts wearing or chipping, it doesn't get better-it only spreads damage. This assembly is what keeps power transferring clean from the driveshaft down to the prop. Getting it back to factory condition makes a big difference in how smooth and dependable the motor feels on the water.. Key Features. Precision-Cut Gear Teeth - Ensures smooth engagement and efficient power transfer through the drivetrain.. Hardened Metal Construction - Built to handle constant load, torque, and long-term wear inside the lower unit.. Balanced Rotation Performance - Helps reduce vibration and maintain consistent operation at all speeds.. Direct OEM Replacement Fit - Matches original specifications for proper alignment and reliable installation.. Engine & Boat Compatibility. Designed for Ya