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Mercury Outboard Lower Unit Replacement – Fits Most 3 & 4 Cylinder – 2.07 & 2.33 Ratios – 2 & 4 Stroke – Aftermarket

Name: Mercury Outboard Lower Unit Replacement – Fits Most 3 &amp; 4 Cylinder – 2.07 &amp; 2.33 Ratios – 2 &amp; 4 Stroke – Aftermarket
SKU: ST-90-205
Availability: InStock
Rating: 4.20 (20 reviews)

Original price was: $1,326.45.Current price is: $1,195.00.

Rated 4.20 out of 5 based on 20 customer ratings

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SKU: ST-90-205 Categories: Mercury Force, Mercury Lower Unit, Standard

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Description
Additional information

Description

Mercury Outboard Lower Unit Replacement – Fits Most 3 & 4 Cylinder Models – 2.07 & 2.33 Ratios – 2 & 4 Stroke – Aftermarket

Upgrade your Mercury outboard with this premium aftermarket lower unit, engineered to replace most Mercury 3 & 4 cylinder models. Designed for both 2-stroke and 4-stroke engines (70–125 HP, 1987 & newer), this unit offers a reliable solution for repairing or restoring your marine performance. Ideal for owners looking for a cost-effective, high-quality replacement that matches OEM standards.

Key Features

Compatible with most Mercury 3 & 4 cylinder 2-stroke outboards (1987 & newer, 70–125 HP)
Also replaces 75–115 HP 4-stroke models below Serial #OT801000
Available in 2.07 & 2.33 gear ratios for optimal performance
Supports both 2-stroke and 4-stroke applications
Aftermarket part with robust construction for durability
Not a fit for 3-jaw lower units without a midsection shift shaft update

Specifications Table

Feature	Details
Fitment	Mercury 3 & 4 Cylinder 2-Stroke (1987+, 70–125 HP)
Additional Fitment	Mercury 4-Stroke 75–115 HP (below Serial #OT801000)
Gear Ratios	2.07:1, 2.33:1
Engine Types	2-Stroke Carb, 2-Stroke DFI, 4-Stroke
Shaft Lengths	20″ (L), 25″ (XL)
Bullet Diameter	4-1/4″
Exclusions	3-jaw lower units (without shift shaft change), plastic water pump models
Ratio Notice	2.31 no longer available; use 2.33 as replacement
Model Range	3 & 4 Cylinder Mercury/Mariner Outboards, see application guide below

Application Guide

Replaces most 3 & 4 cylinder 2-stroke (1987 & newer, 70–125 HP)
Fits 75–115 HP 4-strokes below Serial #OT801000
Will NOT replace a 3-jaw unit without changing the midsection shift shaft
Only for 4-1/4″ bullet diameter cases
Not compatible with models using a plastic water pump housing
You must verify the correct gear ratio (2.07:1 or 2.33:1)
Confirm engine type (2-stroke carb, DFI, or 4-stroke), and shaft length (L/XL/LL)
LL model (22.5″ shaft) not supported

Why Choose This Mercury Lower Unit?

This unit is built to precise specs for long-lasting, reliable operation. Each assembly is thoroughly tested and ready for installation, giving you confidence in both fit and performance. For questions on compatibility, call us with your serial number for expert fitment guidance.

Looking for other Mercury lower unit options?

Browse all Mercury Lower Units here

More Information : Mercury Marine

Additional information

Weight	88 lbs
Dimensions	23 × 13 × 26 in
Ratio/Type/Shaft	2.07/2-Stroke Carb/20" , 2.07/2-Stroke Carb/25" , 2.07/2-Stroke DFI/20" , 2.07/2-Stroke DFI/25" , 2.07/4-Stroke/20" , 2.07/4-Stroke/25" , 2.33/2-Stroke Carb/20" , 2.33/2-Stroke Carb/25" , 2.33/2-Stroke DFI/20" , 2.33/2-Stroke DFI/25" , 2.33/2stroke 50-60HP Bigfoot/20" , 2.33/4-Stroke/20" , 2.33/4-Stroke/25" , 2.33/4stroke 30-50HP Bigfoot/20" , 2.33/4stroke 40-60HP Bigfoot/20" , 2.33/4stroke 40-60HP Bigfoot/25"