Alpha One Gen I Complete Sterndrive 1972-1990 | SEI SE106 | Replaces MerCruiser R MR Alpha One

SEI SE106 — Alpha One Gen I Complete Sterndrive | 1972–1990 | Replaces MerCruiser R, MR & Alpha One | Not Eligible For Free Shipping

SEI SE106 is a complete aftermarket replacement sterndrive for MerCruiser R, MR, and Alpha One Gen I applications from 1972 through 1990. Designed and manufactured by Sterndrive Engineering, Inc. (SEI) as a direct replacement for the original MerCruiser sterndrive, the SE106 fits most MerCruiser applications 228 HP and up within this production window. Available in four gear ratios: 1.47, 1.62, 1.81, and 1.94 — confirm your original sterndrive’s gear ratio before selecting. Ships in two boxes. Comes with a 9-9/16 new style input yoke. Does not include a complete install kit or anode kit — see related items. SEI warranty applies to applications up to 300 HP; SEI does not warranty applications over 300 HP. Not eligible for free shipping.

Confirm Fitment Before Ordering

Confirm your MerCruiser engine model, year, and original sterndrive gear ratio before ordering. Contact us with your engine model, serial number, and current gear ratio by email, text, or live chat and we’ll help confirm SE106 is the correct replacement sterndrive for your application.

Part Specifications

• SEI Part Number: SE106
• Type: Complete sterndrive — aftermarket replacement
• Replaces: MerCruiser R, MR, and Alpha One Gen I sterndrives
• Application Years: 1972–1990
• HP Rating: 228 HP and up (SEI warranty applies up to 300 HP; not warranted over 300 HP)
• Gear Ratios Available: 1.47, 1.62, 1.81, 1.94
• Input Yoke: 9-9/16 new style
• Ships: Two boxes
• Kit Includes: Complete sterndrive assembly
• Not Included: Install kit, anode kit (see related items)
• Vendor: Sterndrive Engineering (SEI)

MerCruiser Model Cross-Reference

• Replaces MerCruiser Sterndrive 225-S (1974)
• Replaces MerCruiser Sterndrive 233 (1975–1977)
• Replaces MerCruiser Sterndrive 250 (1977)
• Replaces MerCruiser Sterndrive 260 (1978–1982)
• Replaces MerCruiser Sterndrive 898/228 (1977–1982)
• Replaces MerCruiser Sterndrive R/MR/Alpha One (1983–1990)
• Typical engine applications 1983–1990: 5.7L, 5.0L (4-barrel carb) | 350, 305 CID (4-barrel carb) | 260, 230, 228 HP

Additional Information

• Vendor: Sterndrive Engineering (SEI)
• Part Number: SE106
• Application: MerCruiser R, MR, Alpha One Gen I — 1972–1990
• Gear Ratios: 1.47, 1.62, 1.81, 1.94
• HP Range: 228 HP and up (warranted to 300 HP)
• Shipping: Not eligible for free shipping — ships in two boxes

Installation Notes

Installation should be performed following the applicable MerCruiser service manual for the Alpha One Gen I sterndrive. An install kit and anode kit are required for proper installation and corrosion protection — see related items for compatible kits. Inspect the transom plate, bellows, and gimbal bearing before installing the replacement sterndrive.

Legal Notice

Brunswick Corporation is the Original Equipment Manufacturer (OEM). Sterndrive Engineering, Inc. (SEI) has no affiliation with Brunswick Corporation. Sterndrive Engineering, Inc. manufactures a sterndrive designed to replace Mercury Marine’s MerCruiser, Alpha One, R, MR, and Gen II sterndrives. MerCruiser, Alpha One, Gen II, R, and MR are trademarks of Brunswick Corporation. As with any aftermarket product, any warranties governing products manufactured and/or sold by Brunswick Corporation will not apply to products manufactured and/or sold by Sterndrive Engineering, Inc. (SEI) or to products damaged due to the operation of an SEI product.

Frequently Asked Questions

Q: How do I determine my correct gear ratio?
A: Your current sterndrive’s gear ratio is stamped on a tag or label on the sterndrive housing, or listed in the MerCruiser parts manual for your engine and sterndrive serial number. The four available ratios are 1.47, 1.62, 1.81, and 1.94. Always match the replacement ratio exactly to the original — changing gear ratio affects propeller selection and performance. Contact us by email, text, or live chat if you need help identifying your ratio.

Q: Does SE106 include the install kit and anode kit?
A: No — the SE106 is the complete sterndrive assembly only. An install kit (bellows, gaskets, fasteners) and anode kit are required for proper installation and corrosion protection and must be purchased separately. See related items for compatible install and anode kits for the SE106.

Q: What is the HP limit for the SEI SE106?
A: SEI rates the SE106 for applications up to 300 HP. SEI does not warranty SE106 units operated in applications exceeding 300 HP. Confirm your engine’s horsepower rating before ordering.

Q: Why choose an SEI sterndrive over a used OEM unit?
A: A used OEM sterndrive of unknown service history introduces risk of worn gears, failed seals, and imminent service needs. The SEI SE106 is a new-build unit manufactured to replace the original MerCruiser design, with a known service baseline and SEI’s warranty coverage for applications up to 300 HP. For a high-use or high-value vessel, a new replacement unit is a more predictable investment than a used OEM pull.

Q: What propeller shaft does the SE106 use?
A: The SE106 uses the standard Alpha One Gen I propeller shaft configuration. Consult your MerCruiser parts manual or contact us with your engine and sterndrive serial number to confirm propeller shaft and hardware compatibility before purchasing a propeller for use with the SE106.