Upper Driveshaft Housing Seal Kit – Fits MerCruiser Alpha One Gen II (Replaces 26-88397A1, 88397A1)

Upper Driveshaft Housing Seal Kit – Fits MerCruiser Alpha One Gen II

This upper driveshaft housing seal kit is designed for MerCruiser Alpha One Gen II stern drives (1991–2010 models, serial numbers 0M400412 and up). It provides the essential seals and gaskets needed to service the upper driveshaft housing, preventing water intrusion and gear lube leaks.

It serves as a direct replacement for multiple OEM and aftermarket part numbers, ensuring broad compatibility for a reliable repair.

• Installation Location: Upper Driveshaft Housing
• Compatible Models: MerCruiser Alpha One Gen II (1991+)
• Kit Contents: Includes three oil seals and one gasket for a complete service.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

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.

Technical Specifications

Package Contents

This kit includes the following components:

• 2 x Oil Seal (Replaces 26-66302)
• 1 x Oil Seal (Replaces 26-823894)
• 1 x Gasket (Replaces 12-19183)

Installation Guide

Professional installation is recommended. The following are general steps for replacement:

1. Drain Gear Lube: Completely drain the gear lube from the sterndrive into a suitable container.
2. Separate Drive Halves: Separate the upper and lower units of the sterndrive.
3. Access Housing: Remove the upper driveshaft housing cover to expose the seals.
4. Remove Old Seals: Carefully remove the old seals and gasket. Note their orientation and order.
5. Clean Surfaces: Thoroughly clean the housing and cover surfaces, removing any old sealant or corrosion.
6. Install New Seals: Press the new seals into place using a proper seal driver, ensuring they are seated squarely without damage.
7. Install Gasket & Reassemble: Place the new gasket on the clean housing surface and reinstall the cover, torquing bolts to manufacturer specifications.
8. Rejoin Drive: Reconnect the upper and lower drive units.
9. Refill & Check: Refill the sterndrive with fresh, high-quality marine gear lube. Check for any leaks before returning to service.

Troubleshooting & FAQ

How do I confirm this seal kit fits my Alpha One Gen II drive?
Check your drive's serial number. This kit is specified for 1991 and newer Alpha One Gen II models, starting from serial number 0M400412 and up. Our compatibility table provides a detailed breakdown of the applicable serial number ranges to help you verify the fit.

What are the signs that my upper driveshaft seals are failing?
Common symptoms include finding water in your gear lube (which gives it a milky, "peanut butter" appearance), noticing a persistent oil sheen on the water around your drive, or observing a visible gear lube leak from the upper housing or weep holes.

Does this kit include everything for the job?
This kit contains the three essential oil seals and one housing gasket required to service the upper driveshaft housing itself. Depending on the extent of your maintenance, additional O-rings or gaskets for other components (like shift shafts or water pumps) may be necessary and are sold separately.

OEM vs. Aftermarket?
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.

How fast do you ship and how much does it cost?
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.

What is your warranty and return policy?
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?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.