MerCruiser Alpha One Gen II U-Joint Assembly – Fits Alpha One Gen II & Vazer (864281A2)

$639.99 $1,023.00

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MerCruiser Alpha One Gen II U-Joint Assembly – Fits Alpha One Gen II & Vazer (864281A2) is backordered and will ship as soon as it is back in stock.

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You may return most new, unopened items within 7 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.

Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This is a direct-replacement MerCruiser Alpha One Gen II U-Joint Assembly, engineered to fit MerCruiser sterndrive applications including Alpha One Gen II models from 1998 and newer (serial number 0L100040 and above) and all Vazer drives.

It serves as a direct interchange for Mercury part numbers 864281A2, 864281A01, 59830A5, 814819A2, 814819A7, and 865491A01.

Designed for direct, hassle-free installation.
Constructed from durable steel to withstand marine environments.
Includes one complete U-Joint assembly as shown.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Mercury	864281A2
Mercury	864281A01
Mercury	865491A01
Mercury	814819A7
Mercury	814819A2
Mercury	59830A5

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Brand	Model	Years	OEM Part No.
MerCruiser	Alpha One Gen II	1998–Newer (S/N 0L100040 and above)	864281A2
MerCruiser	Vazer	All	864281A2

Technical Specs

Product Type: Universal Joint Assembly
Installation: Direct replacement
Housing Material: Steel
Dimensions: 62.0 cm × 23.0 cm × 15.0 cm
Weight: 5.85 kg (12.90 lb)
Warranty: Manufacturer warranty
OEM Part Number: 864281A2
UPC/GTIN: 0745061552418

What’s in the Box

1 x U-Joint Assembly (864281A2)

Installation Notes

Disconnect the boat's battery before starting work.
Safely position the sterndrive in the full tilt position and drain the gear lube.
Remove the sterndrive from the gimbal housing.
Separate the upper and lower units to access the U-joint shaft assembly.
Carefully remove the old U-joint assembly, inspecting the gimbal bearing and bellows for wear or damage.
Clean the input yoke splines and surrounding housing.
Install the new U-joint assembly, ensuring it is properly seated in the yokes.
Reassemble the drive components using new gaskets and seals as recommended by the service manual.
Mount the sterndrive back onto the gimbal housing.
Refill the drive with the correct type and amount of sterndrive gear lube.
Reconnect the battery and test operation in a safe environment.

Troubleshooting & FAQ

How do I know if this U-joint assembly fits my engine?

This assembly is specifically for MerCruiser Alpha One Gen II sterndrives (1998 and newer, S/N 0L100040 and up) and Vazer drives. The most reliable method is to match your existing OEM part number to one of the cross-references listed in our Part Number Matrix.

What are the signs of a failing sterndrive U-joint?

Common symptoms include a clunking, grinding, or clicking noise when turning or shifting, excessive vibration that is felt through the boat, or visible rust and scoring around the U-joint caps. A torn U-joint bellow can also lead to premature failure due to water intrusion.

How often should the U-joints be serviced?

Follow the maintenance schedule in your MerCruiser service manual. Generally, U-joints should be inspected annually for signs of wear, rust, or lack of lubrication. The surrounding bellows should also be checked for cracks or leaks at the same time.

Can I replace just the bearing cross instead of the whole shaft?

While U-joint crosses can sometimes be replaced individually, it requires special tools to press them in and out without damaging the yokes. Replacing the entire assembly is often safer and more reliable, as it ensures all components are new, balanced, and free from fatigue.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

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