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

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

This seal kit is designed for MerCruiser Alpha One Generation II stern drives manufactured from 1991 and newer. It contains the necessary components to seal the upper driveshaft housing and prevent gear oil leaks, a common issue that can lead to the oil monitor reservoir emptying.

This kit is a direct replacement for Mercury/MerCruiser part numbers 26-88397A1 and 88397A1, providing a reliable solution for maintaining your stern drive.

• Application: Seals the upper driveshaft housing on Alpha One Gen II drives (1991+).
• Function: Prevents oil leakage and water intrusion into the gearcase.
• Compatibility: Cross-references with Sierra 18-2644, GLM 87501, and Mallory 9-74302.

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

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

Installation Guide

1. Drain the gear lube from the stern drive unit completely.
2. Separate the upper and lower units of the stern drive to access the driveshaft housing.
3. Carefully remove the old, worn seals and gasket from the upper housing, noting their orientation.
4. Thoroughly clean the sealing surfaces to remove any old adhesive, corrosion, or debris.
5. Apply a light coat of 2-4-C marine grease to the new seals before installation.
6. Carefully press the new seals and gasket into place, ensuring they are properly seated.
7. Reassemble the upper and lower stern drive units, torquing bolts to manufacturer specifications.
8. Refill the stern drive with fresh, high-quality marine gear lube to the proper level.
9. Before operating the boat, inspect carefully for any signs of oil leaks.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my Alpha One Gen II drive?

A: This kit is specifically for MerCruiser Alpha One Generation II stern drives made from 1991 onward (serial number 0M400412 and up). To be certain, please compare your existing part number to the cross-reference list (e.g., 26-88397A1) and review the engine compatibility table.

Q: What are the common symptoms of a failing driveshaft housing seal?

A: The most common sign is a persistent gear oil leak, which can cause the oil monitor bottle on the engine to empty. You might also find water has entered the gearcase, which makes the drained gear lube appear milky or creamy.

Q: How can I tell this is an aftermarket part?

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?

• 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.