Yamaha Lower Unit Assembly – 6G5-45300-21-EK

OEM Yamaha Gearcase Replacement for Reliable Power and Performance

The Yamaha Lower Unit Assembly – 6G5-45300-21-EK is a genuine factory-assembled lower unit designed to restore smooth propulsion, durability, and factory-spec efficiency to your Yamaha outboard. This complete unit arrives pre-assembled with critical internal components—including driveshaft, shift shaft, gears, bearings, and seals—ensuring a precise fit and optimal performance right out of the box.

Built to Yamaha’s exacting standards, this assembly provides corrosion resistance, dependable thrust, and long-lasting service life, making it the trusted choice for boaters facing gearcase damage, saltwater corrosion, or wear-related failure.

Key Features

• OEM Yamaha Quality: Fully assembled by Yamaha for exact tolerances and reliability
• Complete Gearcase: Includes housing, driveshaft, shift shaft, gears, bearings, and seals
• Plug-and-Play Fit: No internal part transfers or guesswork required
• Durable Marine Construction: Built for saltwater resistance and heavy-load operation
• Part Number: 6G5-45300-21-EK (superseded by 6G5-45300-23-EK)

Compatibility

Designed for select Yamaha outboard motors, typically in the 90HP–115HP range. Always verify compatibility using your model year and Yamaha parts diagram, or consult a Yamaha-certified technician before ordering.

Ideal Use Cases

• Impact Damage: Replacement for cracked or severely damaged housings
• Saltwater Corrosion: Prevent performance loss from rusted or leaking seals
• Complete Overhaul: A direct replacement to restore older Yamaha engines to factory reliability

Why Choose Genuine Yamaha?

A lower unit is the heart of your propulsion system. Aftermarket or rebuilt units often compromise performance with mismatched tolerances or reused components. A genuine Yamaha assembly ensures watertight seals, smooth gear operation, and long-term reliability. With the 6G5-45300-21-EK, you eliminate the risks of guesswork and ensure your outboard runs like new.

Frequently Asked Questions

Does this unit ship pre-filled with gear oil?
No. It is shipped dry and requires Yamaha-approved lower unit gear oil before use.

Can I install this unit myself?
Installation can be done by experienced boaters, but Yamaha recommends professional installation for correct alignment, torque, and seal integrity.

Has this part been superseded?
Yes. The 6G5-45300-21-EK has been replaced by 6G5-45300-23-EK, which offers updated fitment and durability improvements.

• Supersessions
  6G5-45300-22-EK, 6G5-45300-23-EK, 6G5-45300-23-EK