Alpha One® Gen I Short Yolk - Complete Sterndrive | Sterndrive Engineering SE104

SEI SE104 — Alpha One Gen I Short Yoke Complete Sterndrive | Drop-In Replacement for MerCruiser 160/165HP | 3-Year Warranty | Made in the USA

When your Alpha One Gen I sterndrive is worn out, the math is simple: rebuild costs, labor time, and downtime add up fast. The SEI SE104 gives you a fully assembled, ready-to-install complete sterndrive replacement — all internal parts included, fully compatible and interchangeable with the OEM drive — at a price that makes rebuilding nearly impossible to justify.

Backed by a 3-year warranty and built to handle up to 300HP, the SE104 is the go-to replacement for older inline 4 and 6-cylinder MerCruiser applications from 1967–1977. MacombMarineParts.com has it in stock and ready to ship.

Application & Specifications:

• Replaces MerCruiser Sterndrive 160HP (1967–1969) with trim and tilt
• Replaces MerCruiser Sterndrive 165HP (1970–1977) with trim and tilt
• Designed for older inline 4 and 6-cylinder engines
• Up to 300HP (SEI does not warranty applications over 300HP)
• Comes with 8-1/8" old-style short input yoke
• Available gear ratios: 1.62 | 1.81 | 1.94

Important — What's Included & What's Not:

• ✅ Complete sterndrive assembly with all internal parts
• ✅ Ships in two boxes (upper and lower halves)
• ❌ Does NOT include Complete Install Kit — see related items
• ❌ Does NOT include Anode Kit — see related items
• ⚠️ Not eligible for free shipping due to size and weight

Additional Information

Why Replace Instead of Rebuild?

At SEI's pricing, a complete replacement drive is often more cost-effective than a full rebuild — especially when you factor in labor, parts sourcing, and the risk of additional wear discovered mid-repair. The SE104 ships fully assembled with all internal components already installed, so your mechanic bolts it on and you're back on the water. No teardown. No surprises.

Every SEI replacement sterndrive is fully compatible and interchangeable with the original MerCruiser OEM drive. All internal parts are included. The only things you'll need to add are the install kit and anode kit — both available as related items on this page.

Why Choose SEI Over OEM or Rebuilt?

• 3-year warranty — longer coverage than most rebuilt units
• All-inclusive assembly — every internal component included, nothing to source separately
• Full OEM compatibility — direct drop-in replacement, interchangeable with MerCruiser Alpha One Gen I drives
• Multiple gear ratios available — 1.62, 1.81, and 1.94 to match your original application
• Up to 300HP rated — built for the full power range of these applications
• Made in the USA — Sterndrive Engineering, Inc. manufactures every drive domestically
• Fraction of OEM cost — at this price point, a new SEI drive is almost always the smarter financial decision vs. a rebuild

Frequently Asked Questions

1. What does "complete sterndrive" mean — what's actually included?
The SE104 is a fully assembled sterndrive unit with all internal parts included — gears, bearings, seals, and housings. It ships in two boxes (upper and lower halves) and is ready to install. You will need to purchase the Complete Install Kit and Anode Kit separately — both are available as related items on this page.

2. Which MerCruiser drives does the SE104 replace?
The SE104 replaces MerCruiser 160HP sterndrives from 1967–1969 and MerCruiser 165HP sterndrives from 1970–1977, both with trim and tilt. It is designed for older inline 4 and 6-cylinder engine applications. If you're unsure whether this is the right drive for your boat, contact us at MacombMarineParts.com before ordering.

3. What gear ratio do I need?
The SE104 is available in 1.62, 1.81, and 1.94 gear ratios. Your gear ratio is typically stamped on the original drive or listed in your engine documentation. If you're not sure which ratio you have, check your owner's manual or contact us — we can help you confirm the correct ratio before you order.

4. What is the short yoke, and do I need it?
The SE104 comes with an 8-1/8" old-style short input yoke, which is the correct configuration for the 1967–1977 MerCruiser 160/165HP applications this drive is designed to replace. If your engine requires a long yoke configuration, you'll need a different model — contact us to confirm before ordering.

5. Is the SEI drive truly compatible with my OEM MerCruiser?
Yes. SEI replacement sterndrives are fully compatible and interchangeable with the original OEM MerCruiser Alpha One Gen I drives. All internal parts are designed to the same specifications. Note: Sterndrive Engineering, Inc. (SEI) has no affiliation with Brunswick Corporation (the OEM manufacturer of MerCruiser). MerCruiser, Alpha One, R, MR, and Gen II are trademarks of Brunswick Corporation. OEM warranties do not apply to SEI products.

6. Why isn't this eligible for free shipping?
Complete sterndrive assemblies are large, heavy freight items — the SE104 ships at approximately 100 lbs in two boxes. Due to the size and weight, standard free shipping thresholds do not apply. Shipping cost will be calculated at checkout based on your location.

7. Does SEI warranty applications over 300HP?
No. SEI's 3-year warranty covers applications up to 300HP. Use in applications exceeding 300HP voids the warranty. The SE104 is designed for the 160/165HP MerCruiser applications listed above, well within the warranty coverage range.