Drive Shaft Adapter – Fits MerCruiser Bravo I, II & III (Replaces 91-43579)

$3.94 $6.00

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Drive Shaft Adapter – Fits MerCruiser Bravo I, II & III (Replaces 91-43579) 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.).

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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

A specialized Drive Shaft Adapter designed for MerCruiser Bravo I, II, and III sterndrive units. This tool is used to install tapered insert retainers into water inlet hoses on all Bravo and Blackhawk drive units, ensuring a proper fit and seal.

This tool serves as a direct interchange for Mercury/MerCruiser 91-43579, Sierra 18-9844, and Quicksilver 41674T.

Engineered for manual installation without the need for complex machinery.
Constructed from a durable, high-strength polymer for long-lasting service life.
The package includes all necessary tools for the insertion task.

Part Number Matrix

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

Brand	Part Number
Mercury/MerCruiser	91-43579
Sierra	18-9844
Quicksilver	41674T

Engine & Model Compatibility

Confirm your engine model and year in the table below to ensure accurate fitment.

For MerCruiser applications, this tool is compatible with a wide range of Bravo, Blackhawk, and other high-performance drive units listed here.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
MerCruiser	Bravo I	Various	N/A	All	91-43579	Drive unit application
MerCruiser	Bravo II	Various	N/A	All	91-43579	Drive unit application
MerCruiser	Bravo III	Various	N/A	All	91-43579	Drive unit application
MerCruiser	Bravo X One	Various	N/A	All	91-43579	Drive unit application
MerCruiser	Bravo X Two	Various	N/A	All	91-43579	Drive unit application
MerCruiser	Bravo X Three	Various	N/A	All	91-43579	Drive unit application
MerCruiser	Bravo XR One	Various	N/A	All	91-43579	Drive unit application
MerCruiser	Bravo XR Sportmaster	Various	N/A	All	91-43579	Drive unit application
MerCruiser	Bravo XR Three	Various	N/A	All	91-43579	Drive unit application
MerCruiser	Bravo XZ One	Various	N/A	All	91-43579	Drive unit application
MerCruiser	NXT1 Drive	Various	N/A	All	91-43579	Drive unit application
MerCruiser	M8 Drive	Various	N/A	All	91-43579	Drive unit application

Technical Specs

Product Type: Service Tool / Insertion Tool
Installation: Manual
Material: Plastic / Polymer
Housing Material: Plastic
Housing Color: Black
Dimensions: 1.0" H x 8.0" W x 10.0" L
Weight: 0.01 kg (0.317 oz)
Warranty: Varies by manufacturer
Other Technical Attributes: Conical tapered design for bell housing insertion

What’s in the Box

1 x Tapered Insert Tool (Replaces 91-43579)
2 x Insert Tools (Replaces 41674T)

Installation Notes

Ensure the sterndrive unit is properly supported and secured before beginning work.
Identify the water inlet hose on the bell housing where the tapered insert retainer is to be installed.
Place the new tapered insert retainer onto the conical end of the adapter tool.
Carefully align the tool and retainer with the opening of the water inlet hose.
Apply steady, even pressure to push the tool, seating the retainer securely into the hose.
Once the retainer is fully seated, gently withdraw the tool.
Visually inspect the installation to confirm the retainer is seated correctly and flush.

Troubleshooting & FAQ

What sterndrive units is this tool specifically for?

This tool is designed for a wide range of MerCruiser sterndrives, including Bravo I, II, III, Bravo X series, Bravo XR series, Blackhawk, NXT1, and M8 drive units.

What is the primary function of this tool?

Its main purpose is to correctly install tapered insert retainers into the water inlet hoses located on the bell housing of the sterndrive unit, ensuring a secure, leak-free fit.

Is this tool difficult to use?

No, it is a straightforward manual tool. You place the retainer on the tool's tapered end and apply firm, even pressure to press it into the hose opening. No special machinery is required.

Can this be used for engine brands other than MerCruiser?

This tool is specifically designed as a direct replacement for MerCruiser tool 91-43579. We do not recommend using it for other brands, as it may not fit correctly.

How do I know if I need this tool?

You will need this tool whenever you are replacing the water inlet hose inserts or performing maintenance that requires their removal and reinstallation. A leaking or improperly seated retainer might also indicate a poor installation where this tool would be needed.

What kind of maintenance does the tool itself require?

The tool requires minimal maintenance. Simply wipe it clean after each use and store it in a dry location to prevent damage. Its polymer construction is designed for durability.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). It has been built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility and batch-inspected for consistency.

Shipping speed & cost

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

Warranty & returns

This product is 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 if the item is unused and in its original condition. See our policy page or reach out for instructions.

Safety & Important Info

Verify images and specifications against your original part before purchase. If anything differs—even if your model appears compatible—do not complete the purchase.
This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component.
Professional installation is highly recommended for safety and optimal performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
Fast Global Fulfillment — We offer free standard delivery to most regions, with typical transit times of 5–15 days.
Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.

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