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Sierra 18-2205 Upper Unit Gear Set for MerCruiser Stern Drives 1.98:1 Ratio

Manufacturer

Sierra

<p>For nearly six decades, Sierra has established itself as one of the marine industry's most trusted names in aftermarket engine and drive parts. Founded as a specialized marine parts manufacturer, Sierra has grown into a comprehensive supplier of replacement components, instrumentation, and accessories for both recreational and commercial boating applications. Operating from their 300,000-square-foot distribution center in Litchfield, Illinois, Sierra serves boat owners and marine technicians worldwide with an extensive catalog of parts engineered specifically for the harsh saltwater environment.</p><h3>Marine Engine Excellence</h3><p>Sierra's reputation was built on delivering precision-engineered internal engine components and drive system parts that meet or exceed OEM specifications. Their <a href="/7570-sierra-engine-gasket-set-5404">engine gasket sets</a> provide critical sealing solutions for inboard and outboard motors, while their <a href="/7570-sierra-engine-complete-assembly-15341">engine complete assemblies</a> offer comprehensive replacement options for major overhauls. Each component undergoes rigorous testing to ensure reliability in demanding marine conditions, from corrosion resistance to temperature cycling performance.</p><h3>Instrumentation and Monitoring Systems</h3><p>Accurate instrumentation is essential for boat operators to monitor engine health and prevent costly breakdowns on the water. Sierra's comprehensive line of <a href="/7570-sierra-gauges-200483">gauges</a> includes everything from fuel pressure and temperature indicators to voltmeters and trim gauges, all designed with marine-grade materials that withstand vibration, moisture, and UV exposure. Their <a href="/7570-sierra-tachometer-gauge-1488">tachometer gauges</a> deliver precise RPM readings critical for optimizing engine performance and fuel efficiency. Supporting these instruments, Sierra's <a href="/7570-sierra-gauge-resistor-47908">gauge resistors</a> ensure proper signal conditioning and accurate readings across various sensor types and engine configurations.</p><h3>Expanded Product Portfolio</h3><p>In 2022, Sierra significantly broadened its scope beyond traditional marine engine parts to encompass a wider range of boating accessories and even outdoor power equipment components. This strategic expansion brought established marine brands like Shields and Moeller under the Sierra umbrella, creating a one-stop resource for marine maintenance and replacement parts. The company now offers fuel systems, electrical components, battery charging solutions, and NMEA electronics alongside their traditional engine parts lineup.</p><h3>Quality Backed by Industry-Leading Warranties</h3><p>What sets Sierra apart in the crowded aftermarket marine parts market is their commitment to standing behind every component they manufacture. Their warranty coverage extends beyond simple part replacement—it includes shop labor, haul-out fees, towing charges, and related incidental costs should a warrantied part fail. This comprehensive protection reflects the company's confidence in their manufacturing processes and quality control standards. For boat owners facing repairs far from shore or mechanics working on customer vessels, this peace of mind is invaluable. Whether you're maintaining an outboard motor, rebuilding an inboard engine, or upgrading your boat's instrumentation, Sierra's decades of marine industry experience and commitment to quality make them a reliable choice for keeping your vessel running at peak performance.</p>

Part Number

18-2205
08/03/2036 7:23 AM
Sale Price

$502.69

2 left at this price

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Usually delivered within 2 days

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Fitment guaranteed

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Product Details

The Sierra 18-2205 is a replacement upper unit gear set engineered for MerCruiser stern drive applications with a 1.98:1 gear ratio. It directly replaces OEM part number 43-55778A3 and is also interchangeable with Mercruiser stern drive part numbers 43-55766A2 and 43-55766A3, as well as GLM part number 11240.

This gear set features a 20-tooth drive gear and a 24-tooth driven gear, providing the correct ratio for compatible 4-cylinder sterndrive units. Each Sierra product is manufactured to meet or exceed the specifications of the original equipment part it replaces, ensuring reliable, long-lasting performance.

Key Features:

  • 1.98:1 upper unit gear ratio
  • Drive gear: 20 teeth; Driven gear: 24 teeth
  • Includes one drive gear and one driven gear per package
  • Meets or exceeds OEM specifications
  • Direct replacement for MerCruiser OEM part 43-55778A3

OEM Cross-Reference Numbers:

  • Mercruiser: 43-55778A3, 43-55766A2, 43-55766A3
  • GLM: 11240
  • Sierra: 18-2205

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Placed order on Sunday and received shipment on Thursday. Haven't installed items yet but boxes are in good shape. I'm satisfied with the transaction.

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A service

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It may have taken a little while to ship, but it is definitely the best bang for the buck. I will definitely be looking here again for my needs.

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