Shift Cable Bellow for Mercruiser Alpha One Gen 1 Gen 2 Bravo One Bravo 2 Bravo 3 – 74639A2
This shift cable bellow is designed to fit all Mercruiser sterndrive models, including Alpha One Gen 1 & Gen 2, Bravo One, Bravo 2, and Bravo 3. It provides a critical seal to protect the shift cable from water intrusion and contaminants, ensuring smooth and reliable shifting performance.
This part directly replaces Mercury 74639A2 and Sierra 18-2753-1, making it a versatile aftermarket solution for maintaining your sterndrive system.
- Fits all Mercruiser drives including Alpha One and Bravo series
- Includes mounting clamps for complete installation
- Essential protection component for shift cable assemblies
Part Number Cross-Reference
Use this table to confirm equivalent part numbers across OEM and aftermarket brands.
| Brand |
Part Number |
| Mercury |
74639A2 |
| Sierra |
18-2753-1 |
Compatible Engine Models
Confirm your engine model/year in the table below. For Mercury owners, here's a guide to help you identify your engine's serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.
| Brand |
Model |
Notes |
| Mercruiser |
Alpha One Gen 1 |
All sterndrive models |
| Mercruiser |
Alpha One Gen 2 |
All sterndrive models |
| Mercruiser |
Bravo One |
All sterndrive models |
| Mercruiser |
Bravo 2 |
All sterndrive models |
| Mercruiser |
Bravo 3 |
All sterndrive models |
Technical Specifications
| Specification |
Value |
| OEM Part Number |
74639A2 |
| Aftermarket Part Number |
Sierra 18-2753-1 |
| Application |
Shift Cable Protection Bellow |
| Compatibility |
All Mercruiser Drives (Alpha One Gen 1 & 2, Bravo One, 2, 3) |
Package Contents
- 1 × Shift Cable Bellow
- Includes Clamps
Installation Guide
- Disconnect the shift cable from the sterndrive unit and secure the boat on a stable work surface. Ensure the engine is turned off and the battery is disconnected.
- Remove the old shift cable bellow by loosening and removing the existing clamps. Carefully slide the bellow off the shift cable assembly.
- Inspect the shift cable for any signs of corrosion, damage, or wear before installing the new bellow.
- Slide the new shift cable bellow onto the shift cable assembly, ensuring it is properly seated at both ends.
- Install the provided clamps at both ends of the bellow. Tighten the clamps securely to prevent water intrusion.
- Verify that the bellow is not twisted or kinked and that it allows full range of motion for the shift cable.
- Reconnect the shift cable to the sterndrive unit and test the shifting mechanism for smooth operation.
- Perform a final inspection to ensure all clamps are tight and the bellow is properly sealed.
Troubleshooting & FAQ
Q: How do I confirm this shift cable bellow fits my sterndrive?
A: This bellow fits all Mercruiser Alpha One Gen 1 & 2 and Bravo One, 2, and 3 drives. Cross-reference your existing part number (Mercury 74639A2 or Sierra 18-2753-1) or consult your sterndrive manual to verify compatibility.
Q: How often should I replace the shift cable bellow?
A: Inspect the shift cable bellow annually during routine maintenance. Replace it immediately if you notice any cracks, tears, or signs of wear, as a damaged bellow can allow water to enter the drive unit and cause serious damage.
Q: What are the signs that my shift cable bellow needs replacement?
A: Common signs include visible cracks or tears in the rubber, water inside the drive unit, difficulty shifting gears, or corrosion around the shift cable assembly. Regular visual inspections can help catch problems early.
Q: Do the clamps come with this bellow?
A: Yes, this package includes the mounting clamps needed for installation, so you have everything required to complete the job.
Q: OEM vs. Aftermarket?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.
Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.
Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.
Important Notes
- Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
- This product is an aftermarket replacement part and is not an OEM component.
- Professional installation is recommended to ensure safety and optimal performance.
Why Choose JLM MARINE?
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Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
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Fast Global Shipping: Free delivery worldwide in 5–15 days.
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Direct from Manufacturer: Competitive pricing without compromising quality.