Yamaha Replacement Lower Unit | 25" | 4 Stroke | 90-418-B25F

<h2>Yamaha® Replacement Lower Unit — 25″ 4-Stroke</h2>

<p><strong>Restore performance and reliability.</strong> This premium Yamaha replacement lower unit is engineered to meet or exceed factory specifications. The complete gearcase arrives <em>fully assembled and ready to install</em> for smooth shifting, long service life, and dependable on-water performance.</p>

<h3>Highlights</h3>
<ul>
  <li><strong>Direct-fit replacement</strong> — designed for Yamaha 4-Stroke outboards with a <strong>25″ shaft</strong></li>
  <li><strong>OEM-level engineering</strong> — precision-machined gears and shafts for reliable operation</li>
  <li><strong>Fully assembled</strong> — pre-built with water pump &amp; internal components installed</li>
  <li><strong>Quality-tested</strong> — each unit inspected for fit, finish, and durability</li>
  <li><strong>Part #</strong> <code>90-418-B25F</code> — replaces select OEM Yamaha lower units</li>
</ul>

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  <strong>Compatibility Note:</strong> Ensure your outboard requires a <strong>25″</strong> shaft lower unit. Verify gear ratio and rotation if applicable.
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<h3>Application</h3>
<p>Fits Yamaha 4-Stroke outboards requiring a <strong>25″ shaft</strong> lower unit. Please confirm model, year, and gear ratio before ordering.</p>

<p><strong>Need help confirming fitment?</strong> <a href="https://marinepartsco.com/pages/contact">Contact us</a> for quick application assistance.</p>

<p style="font-size:0.9em;opacity:0.8;"><em>Yamaha® is a registered trademark of Yamaha Motor Co., Ltd. Use of the name is for reference only and does not imply affiliation or endorsement.</em></p>