Marine-grade aftermarket gearbox trim tab sacrificial anode for selected 35 HP, 40 HP, 45 HP, 50 HP, 60 HP and 70 HP Mercury / Mariner 2-stroke outboard engines.

Designed to help protect the gearbox and lower unit against galvanic corrosion while providing a trim tab for steering torque adjustment.

Main Part Number: 31640Q04

Available in Zinc or Aluminium.

Choose Your Anode Material

Zinc Anode

Traditional sacrificial anode material
Particularly suitable for saltwater applications

Aluminium Anode

Marine-grade aluminium alloy
Suitable for saltwater and brackish water applications
Lightweight alternative to zinc

Please follow the engine manufacturer's recommendations when selecting anode material.

Fitment – Mercury / Mariner Outboards

2-Stroke Models

Suitable for selected:

35 HP – 2-Stroke
40 HP – 2-Stroke
45 HP – 2-Stroke
50 HP – 2-Stroke
60 HP – 2-Stroke
70 HP – 2-Stroke

Important Fitment Notes

Mercury and Mariner used different gearbox and trim tab designs across engine generations.

Compatibility depends on:

Engine model and horsepower
Engine production year
Engine serial number
Gearbox configuration
Original trim tab part number

Not suitable for all Mercury / Mariner engines within the listed horsepower range.

Please confirm the original part number and trim tab design before ordering.

Replaces Mercury / Mariner Part Numbers

Main Reference

31640Q04

Additional References Supplied

316404
316406
31640A4
31640B4
31640Q03
31640Q4
97-31640Q4
97-31640T4
97-31640T6
97-8M0059338

The references above are supplied as cross-reference information. Confirm compatibility with the relevant Mercury parts diagram where necessary.

OEM part numbers are used for identification and compatibility reference only.

Product Details

Product Type: Gearbox Trim Tab Anode
Material: Zinc or Aluminium
Application: Mercury / Mariner Outboards
Horsepower: 35, 40, 45, 50, 60 and 70 HP
Engine Type: 2-Stroke
Location: Gearbox / Lower Unit
Purpose: Sacrificial corrosion protection
Additional Function: Steering torque adjustment
Quality: Marine-grade aftermarket replacement
Quantity: 1 anode

Package Includes

1 × Gearbox Trim Tab Anode

Supplied in your selected material:

Zinc
Aluminium

Mounting hardware is not included unless otherwise specified.

Important Compatibility Information

Before ordering, please check:

Exact Mercury / Mariner engine model
Engine horsepower
Engine production year and serial number
Gearbox configuration
Original trim tab part number
Existing anode shape and dimensions
Required anode material

If the part looks the same as yours, this does not always mean it is the correct part for your outboard.

If unsure, please contact SSI Marine with your engine model and serial number for assistance.

Why Buy From SSI Marine?

Workshop-tested aftermarket & OEM-spec parts
Same-day dispatch before 1 PM Monday–Friday
Royal Mail Tracked 24
UK stock – collection available from Leigh, Greater Manchester
Technical support from experienced outboard specialists

Buyer Responsibility

Please confirm compatibility with your exact Mercury / Mariner engine model, serial number and gearbox configuration before purchase.

35–70 HP Mercury Mariner Outboard Trim Tab Anode 31640Q04 – Zinc / Aluminium