SeaSierra upper unit seal kit for Mercruiser Alpha One Gen 2 shows tight, precise fit.
SeaSierra O-ring set demonstrates robust sealing for maintenance tasks.
SeaSierra oil seals illustrate durable shaft sealing for stern drive upkeep.
SeaSierra 26-88397 seal component ready for upper gearcase installation.
SeaSierra drain screw gasket provides leak-resistant drain connection.
SeaSierra seal ring gasket supports proper assembly and seal integrity.
SeaSierra installation visuals highlight compatibility with Mercruiser Alpha One Gen 2.
SeaSierra upper unit seal kit for Mercruiser Alpha One Gen 2 shows tight, precise fit.
SeaSierra O-ring set demonstrates robust sealing for maintenance tasks.
SeaSierra oil seals illustrate durable shaft sealing for stern drive upkeep.
SeaSierra 26-88397 seal component ready for upper gearcase installation.
SeaSierra drain screw gasket provides leak-resistant drain connection.
SeaSierra seal ring gasket supports proper assembly and seal integrity.
SeaSierra installation visuals highlight compatibility with Mercruiser Alpha One Gen 2.

SeaSierra 88397A1 Upper Unit Seal Kit for Mercruiser Alpha One Gen 2 Stern Drive | 26-88397A1 18-2644

OverviewSeaSierra’s 88397A1 Upper Unit Seal Kit is crafted for Mercruiser Alpha One Gen 2 stern drives, providing...
Vendor: SeaSierra
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SeaSierra upper unit seal kit for Mercruiser Alpha One Gen 2 shows tight, precise fit.

SeaSierra 88397A1 Upper Unit Seal Kit for Mercruiser Alpha One Gen 2 Stern Drive | 26-88397A1 18-2644

£40.26
SeaSierra upper unit seal kit for Mercruiser Alpha One Gen 2 shows tight, precise fit.
SeaSierra O-ring set demonstrates robust sealing for maintenance tasks.
SeaSierra oil seals illustrate durable shaft sealing for stern drive upkeep.
SeaSierra 26-88397 seal component ready for upper gearcase installation.
SeaSierra drain screw gasket provides leak-resistant drain connection.
SeaSierra seal ring gasket supports proper assembly and seal integrity.
SeaSierra installation visuals highlight compatibility with Mercruiser Alpha One Gen 2.

SeaSierra 88397A1 Upper Unit Seal Kit for Mercruiser Alpha One Gen 2 Stern Drive | 26-88397A1 18-2644

£40.26
Description
Description
x

Overview

SeaSierra’s 88397A1 Upper Unit Seal Kit is crafted for Mercruiser Alpha One Gen 2 stern drives, providing a cohesive set of seals for the upper gearcase. This aftermarket kit replaces common OEM references such as 26-88397A1, 88397A1, Mallory 9-74302, GLM 87501, and Sierra 18-2644, offering a ready-to-install solution that supports dependable maintenance routines on the water.

What’s included

  • O-rings: 25-25439, 25-35027, 25-35984, 25-70937, 25-32546
  • Oil seals: 26-32080, 26-37259
  • Seal: 26-88397
  • Drain screw gasket: 12-19183, 12-20260
  • Seal ring gasket: 26-45577

Compatibility and fit

  • Mercruiser Alpha I Gen II 1991–1995 (0D469859–0F679999)
  • Mercruiser Alpha I Gen II 1996 and up (0F680000 & Up)
  • Replaces OEM references: 26-88397A1, 88397A1, Mallory 9-74302, GLM 87501, Sierra 18-2644

Why choose SeaSierra

SeaSierra has a long-standing history in marine engine parts since 1987, blending OEM heritage with aftermarket reliability. This kit is designed to simplify maintenance, minimize downtime, and support steady operation by supplying matched components that work together as a seal system for the upper gearcase. Expect crisp fit, consistent material quality, and a package built to withstand the saltwater environment typical of Mercruiser installations.

Real-life use and benefits

During routine season prep or after a stern drive service, this kit helps recreate a tight, dry seal around the drive shaft. While results can vary by application, the combination of seals and O-rings is intended to help maintain proper lubrication, reduce leaks, and preserve the gearcase’s integrity over time. The set is ideal for boaters who perform regular maintenance, owners who value a complete, vetted replacement, and technicians who appreciate a consolidated kit with OEM-equivalent parts.

Usage tips

  • Inspect all mating surfaces for damage before installation.
  • Replace all O-rings and seals as a set to promote uniform sealing performance.
  • Follow standard torque and lubrication guidelines during reassembly.

Note: This kit offers a practical upgrade path and maintenance option, but individual results depend on installation accuracy and operating conditions.

FAQ

Q: Is this kit compatible with Mercruiser Alpha One Gen 2 stern drives?

A: Yes. It is designed for Alpha One Gen 2 (1991–1995 and 1996+ ranges) and replaces OEM references like 26-88397A1 and 18-2644.

Q: What does the SeaSierra 88397A1 Upper Unit Seal Kit include?

A: It includes all O-rings, oil seals, seals, drain gaskets, and the seal ring gasket listed in the product features.

Shipping & Return
Shipping & Return
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Returns Policy

You may return most new, unopened items within 30 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.

Shipping

We can ship to virtually any address in the world. Note that there are restrictions on some products, and some products cannot be shipped to international destinations.

When you place an order, we will estimate shipping and delivery dates for you based on the availability of your items and the shipping options you choose. Depending on the shipping provider you choose, shipping date estimates may appear on the shipping quotes page.

Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.

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