Yamaha - Lower Unit Assembly - Gearcase & Propulsion System - 6H3-45300-17-8D

Overview

When a lower unit goes, you don’t always get much warning—and it usually happens at the worst time. I’ve replaced enough of these to know that a complete assembly saves a lot of guesswork compared to piecing things back together. It’s the backbone of how your motor puts power into the water, so everything has to be right. Swapping in a solid unit like this gets you back to running smooth and confident again.

Key Features

• Complete Gearcase Assembly – Provides a full replacement solution for worn or damaged lower units.
• Smooth Power Transfer – Delivers consistent power from the engine to the propeller for reliable performance.
• Factory-Matched Fit – Built to Yamaha specifications for proper alignment and installation.
• Durable Internal Construction – Designed to handle load, impact, and continuous use in marine conditions.
• Updated Replacement Part – Replaces earlier versions to maintain current performance and fit standards.

Engine & Boat Compatibility

Designed for Yamaha outboards using compatible gearcase and lower unit configurations. Commonly used on small to mid-size engines found on fishing boats, skiffs, and recreational vessels. Always verify compatibility with your specific engine and setup before installation.

FAQ

Q: What are signs my lower unit needs to be replaced?
A: Grinding noises, water in the gear oil, loss of power, or failure to stay in gear are common signs.

Q: Can I rebuild instead of replacing the whole unit?
A: You can, but a full assembly is often faster and more reliable, especially if multiple components are worn.

Q: Does this come ready to install?
A: It’s assembled, but you’ll still need to transfer components like the propeller and check alignment during install.

Q: How does saltwater affect a lower unit?
A: Saltwater can accelerate corrosion and wear, especially if not flushed and maintained regularly.

Q: Should I check anything else during installation?
A: It’s a good time to inspect the water pump, seals, and shift linkage while everything is accessible.

• Supersessions
  6H3-45300-16-4D, 6H3-45300-17-4D, 6H3-45300-18-8D, 6H3-45300-20-8D, 6H3-45300-20-8D