Yamaha - Lower Unit Assembly - Complete Drivetrain - 6K5-45300-13-4D

Overview

The Yamaha Lower Unit Assembly | 6K5-45300-13-4D is what really puts your engine’s power to work in the water. When a lower unit starts going bad, you’ll hear it first—then feel it through vibration or loss of push. At that point, chasing individual parts can turn into a headache, so dropping in a complete unit like this just makes sense. It’s the kind of fix that gets you back on the water with confidence instead of second-guessing every run.

Key Features

• Complete Gearcase Assembly – Includes core internal components for full lower unit operation.

• Smooth Power Transfer – Delivers engine output efficiently to the propeller.

• Corrosion-Resistant Build – Designed to handle saltwater and freshwater exposure.

• OEM Fit and Alignment – Matches Yamaha specifications for proper installation and performance.

• Superseded Replacement Design – Updated by a newer part number for continued support.

Compatibility

Compatible with select Yamaha outboard engines using this lower unit configuration.
Commonly used in Yamaha mid-range outboards with matching gearcase design.
Always confirm compatibility using your engine model and part number.

FAQs

Q: What are signs my lower unit needs replacement?
A: Grinding noise, vibration, water in gear oil, or loss of propulsion.

Q: What does it mean that this part is superseded?
A: Yamaha replaced it with an updated version, which is now the preferred option.

Q: Can I rebuild my lower unit instead?
A: You can, but if multiple components are worn, replacement is usually more reliable.

Q: How important is gear oil maintenance?
A: Very—clean gear oil helps extend the life of internal gears and bearings.

Q: Is this a difficult install?
A: It’s manageable with experience, but proper alignment and sealing are key.

WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to P65Warnings.ca.gov.

• Supersessions
  6K5-45300-12-4D, 6K5-45300-14-4D, 6K5-45300-15-4D, 6K5-45300-15-4D