MERCRUISER DRIVE REPLACEMENTS
Alpha OneĀ® Gen II Sterndrives (1991-Present)
SHOP BY COLLECTION
Explore Alpha OneĀ® Gen II Sterndrives (1991-Present)
The Right Fit for Every MerCruiser Application
Explore Alpha One Gen I, Alpha One Gen II, and Bravo sterndrives with clear fitment details and support for confident selection.
Organized by Assembly Type
Browse complete Alpha One Gen I, II and Barvo sterndrives, upper units and lower units according to the assembly you need.
Ratio & Yoke Verification
Compare the existing gear ratio and input-yoke style before choosing an Alpha One Gen I replacement.
Secure Online Checkout
Place your MerCruiser sterndrive order through protected online payment processing.
Product Selection Support
Send your drive details and identification photos if you need help choosing the correct replacement configuration.
Check Included and Required Installation Components
Shop Alpha One Gen II by Assembly Type
Standard vs Counter-Rotation Alpha One Gen II Drives
Complete Sterndrive vs Upper vs Lower Unit
Choose the Alpha One Gen II assembly that matches the failed, damaged, or missing component. If one half of the existing drive will remain in service, its compatibility with the replacement half must be confirmed.
Complete Sterndrive
- Includes a matched upper and lower drive assembly when confirmed in the listing
- Appropriate when the complete outdrive requires replacement
- Available in multiple listed Alpha One Gen II gear ratios
- Offered in standard and selected counter-rotation configurations
- Product-specific accessories may be sold separately
- Ratio and rotation must be verified before ordering
Upper Gear Unit
- Replaces the upper gear housing assembly
- Must be compatible with the retained lower unit
- Organized by listed ratio applications
- Standard and modified configurations may be separate products
- Does not replace the lower gearcase
- Overall drive ratio must still be confirmed
Lower Unit
- Replaces the lower gearcase assembly
- Standard, ratio-specific, and counter-rotation options are available
- Must match the retained upper and complete-drive application
- Rotation cannot be selected from appearance alone
- Product-specific included components must be reviewed
- Final selection should follow the exact PDP information
Alpha One Gen II Gear Ratio and Selection Guide
| Shopping Path & Available Listing Coverage | Verify Before Ordering |
|---|---|
| Complete Standard Sterndrive ā Current SE116 listings include 1.47, 1.62, 1.81, 1.94, 2.00 and 2.40 ratios | Confirm the existing overall ratio, drive identifiers, rotation, and included components |
| Complete Counter-Rotation Sterndrive ā Current observed applications include 1.47, 1.62, 1.81 and 1.94 ratios | Confirm the counter-rotation requirement, gear ratio, and standard or modified configuration |
| Standard Lower Unit ā Standard SE116 lower-unit application | Confirm compatibility with the retained upper unit and complete-drive configuration |
| Ratio-Specific Lower Unit ā SE116 90-116-02H is listed for supported 2.00 and 2.40 ratio applications | Confirm the existing overall ratio and current product number |
| Counter-Rotating Lower Unit ā Separate SE116 counter-rotating lower-unit application | Confirm rotation, retained upper unit, and complete-drive configuration |
| Upper Gear Unit ā Current groupings include 1.47, 1.62/2.00, 1.81 and 1.94/2.40 applications | Confirm the required upper and lower combination and overall drive ratio |
| Modified Conversion Unit ā Selected modified and Cobra-conversion listings | Confirm the exact conversion system and required configuration |
| Transom and Hydraulic Products ā Transom assemblies, trim products, and hydraulic components | Confirm the existing transom system and required component number |
What Customers Say
Seamless SE116 fit for 1999 5.7L V8
Finding the right Alpha One Gen II replacement on Mariners Warehouse was straightforward. The SE116 with the 1.47:1 gear ratio matched my 1999 5.7L Mercruiser perfectly. The internal impeller in the Gen II lower unit was pre-installed, making the bolt-on installation very smooth.
Exact 1.81 gear ratio match for 4.3L V6
Replaced a worn drive on my 1996 bowrider. The collection page clearly explained how to match engine size to the correct SE116 gear ratio. The 1.81 unit bolted directly to my Gen II transom assembly without needing any modification.
Clear guidance for 3.0L 4-Cylinder (2.00:1 ratio)
The product specs on this Mariners Warehouse collection page helped me identify the 2.00:1 ratio needed for my 2003 3.0L Mercruiser. Packaging was solid with heavy-duty foam, and it solved all my gear grinding issues.
Counter-rotation SE116 for twin engine setup
I ordered the counter-rotation Alpha One Gen II drive for the port side on my 2001 cruiser. The collection details made it easy to distinguish LH from RH rotation. Fits 1991-present setups as advertised.
Spot-on compatibility for 2005 5.0L MPI
Upgraded my damaged outdrive with this SE116 complete unit. The 1.62:1 ratio for my 5.0L MPI was easy to confirm using the engine details on the site. Shift cables reattached easily and water pressure is excellent.
Clear distinction between Gen I and Gen II specs
The product description accurately highlights why Gen II drives (1991-Present) won't fit older Gen I transom plates. That technical clarity saved me from ordering the wrong drive for my 1994 setup. Highly recommend.
Great packaging and smooth break-in
Purchased the full Alpha One Gen 2 replacement drive. Delivery was prompt and well-protected in a reinforced box. After completing the 10-hour gear oil break-in, it runs super quiet on the water.
Frequently Asked Questions
How do I identify the correct Alpha One Gen II sterndrive?
Start with the sterndrive serial number and identification labels rather than appearance alone. Collect the engine serial number, drive serial number, current part number, existing gear ratio, rotation, and required assembly type before selecting an Alpha One Gen II replacement sterndrive.
What is the difference between Alpha One Gen I and Gen II?
Alpha One Gen I and Alpha One Gen II are separate MerCruiser drive families with different applications and components. Do not assume that complete drives, upper units, or lower units can be exchanged between the two generations without product-specific fitment confirmation.
Should I buy a complete sterndrive, upper unit, or lower unit?
Buy the assembly that matches the failed, damaged, or missing component. A complete Alpha One Gen II sterndrive combines compatible upper and lower assemblies when confirmed in the listing, while upper- and lower-only replacements must work with the retained half.
How do I choose the correct Alpha One Gen II gear ratio?
Match the replacement to the verified overall gear ratio of the existing drive and its confirmed application. Do not select a 1.47, 1.62, 1.81, 1.94, 2.00, or 2.40 ratio solely from horsepower, boat size, or a generic online chart.
What is the difference between standard and counter rotation?
Standard and counter-rotation Alpha One Gen II drives support different propeller-rotation requirements. Confirm rotation from the existing drive information and actual configuration instead of choosing from port or starboard position alone.
Is the SEI SE116 a genuine Mercury OEM sterndrive?
No. The SEI SE116 is an aftermarket replacement sterndrive manufactured by SEI Marine. SEI states that it is not affiliated with Mercury Marine or Brunswick Corporation.
Which Alpha One Gen II lower unit is used for 2.00 or 2.40 ratios?
SEI lists the 90-116-02H lower unit for supported 2.00 and 2.40 ratio applications. Final selection still requires confirmation from the existing drive identifiers, retained upper unit, and exact product listing.
Does an SE116 complete drive include the installation and anode kits?
Reviewed SEI complete-drive listings state that the complete installation kit and anode kit are sold separately. Check the exact product page because included hardware, fittings, lubricants, and other components can vary by listing.
What warranty applies to an SEI Alpha One Gen II replacement?
SEI currently lists a three-year fault-free warranty for eligible assembled sterndrive halves, while other parts can have different warranty terms and exclusions. Review the selected product page and the current written warranty policy before purchase.
What information should I send for Alpha One Gen II fitment help?
Send the engine and sterndrive serial numbers, current part number, existing gear ratio, standard or counter rotation, required assembly type, and clear photos of the identification labels. Complete information helps narrow the available Alpha One Gen II replacement options.
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