Gearbox / Lower Unit Seal Kit for Mercury & Mariner Outboards

Marine-grade aftermarket gear housing / lower unit seal kit for selected Mercury and Mariner 40 HP–125 HP outboards.

Suitable for a wide range of selected 2-stroke, 4-stroke, BigFoot and 4-cylinder gearcase applications.

Replaces Mercury / Mariner 26-43035A4 and earlier versions of the same seal kit.

Fitment

Fits selected Mercury & Mariner outboards using the compatible gear housing.

2-Stroke Applications

Selected:

40 HP
45 HP
50 HP
55 HP
60 HP
65 HP
70 HP
75 HP
80 HP
90 HP
100 HP – 4 Cylinder
115 HP – 4 Cylinder
125 HP – 4 Cylinder

Common 100 / 115 / 125 HP 2-Stroke Applications

Suitable for selected 4-cylinder Mercury / Mariner 2-stroke engines, including gearcases equipped with:

3-jaw reverse clutch
6-jaw reverse clutch

4-Stroke Applications

Used on selected Mercury / Mariner 4-stroke gearcases including:

40 HP 4-Stroke
50 HP 4-Stroke / BigFoot
60 HP 4-Stroke / BigFoot
75 HP 4-Stroke
80 HP 4-Stroke
90 HP 4-Stroke
100 HP EFI 4-Stroke
115 HP 4-Stroke

Engine / Gearcase Types

Depending on engine serial number, this seal kit is used on selected:

Mercury Outboard
Mariner Outboard
2-Stroke
4-Stroke
BigFoot
3-Cylinder gearcases
4-Cylinder gearcases
3-jaw reverse clutch gearcases
6-jaw reverse clutch gearcases

Replaces / Cross References

Mercury / Mariner

26-43035A4
43035A4
26-43035A3
43035A3
26-43035A2
43035A2
26-43035A1
43035A1

Aftermarket Cross References

Sierra 18-2626
GLM 87590
Mallory 9-74200

OEM and aftermarket part numbers are used for identification purposes only.

Product Details

Complete gearbox / gear housing seal kit
For selected Mercury & Mariner outboards
Selected 40 HP–125 HP applications
Selected 2-stroke and 4-stroke engines
Suitable for selected BigFoot gearcases
Suitable for selected 3-cylinder and 4-cylinder gearcases
Replaces Mercury 26-43035A4
Replaces earlier 26-43035A1 / A2 / A3
Marine-grade aftermarket replacement
Designed for lower unit servicing and overhaul

Package Includes

1 × Gear Housing / Lower Unit Seal Kit

Kit contains the seals, O-rings and gaskets supplied for the compatible gear housing application.

IMPORTANT – Gearcase & Serial Number Must Be Checked

This kit does NOT fit every Mercury or Mariner 40–125 HP outboard.

Mercury used different lower units and seal kits on engines with the same horsepower and similar years.

Compatibility depends on:

Exact horsepower
Engine model
Engine serial number
2-stroke or 4-stroke
Number of cylinders
Standard or BigFoot gearcase
Gearcase configuration
Original seal kit / part number

100 HP / 115 HP / 125 HP 2-Stroke

This kit is particularly common on selected 4-cylinder 100 HP, 115 HP and 125 HP Mercury / Mariner 2-stroke outboards and can be used with compatible 3-jaw or 6-jaw reverse clutch gearcases.

Do not order this kit based on horsepower alone.

If you are unsure, send SSI Marine your engine serial number before ordering and we can check the correct gearbox seal kit.

Why Buy From SSI Marine?

Workshop-tested aftermarket & OEM-spec parts
More than 10 years supplying outboard parts
UK stock
Same-day dispatch before 1 PM Mon–Fri
Royal Mail Tracked 24
Collection from Leigh, Greater Manchester
Technical support available

Buyer Responsibility

Please confirm compatibility with your exact engine model, serial number and gearcase before purchase.

A similar-looking seal or matching horsepower does not guarantee that this is the correct gearbox seal kit.

40 HP-125 HP Mercury Mariner Outboard Gearbox Lower Unit Seal Kit 26-43035A4 18-2626