Hook (Problem → Solution)

If your Mercury 3.0L outboard lower unit is worn, noisy, or failing under load, replacing it quickly is critical to avoid downtime on the water. The SE216 lower unit replacement is built as a dependable aftermarket solution designed to restore smooth operation, proper gear engagement, and long-term reliability.

Product Overview

The SE216 lower unit is engineered to replace many Mercury 3.0L outboard lower units (serial number 1B504989 and below). Built with marine-grade internal components and precision gearing, this assembly is designed for boaters who want a reliable replacement without the high cost of OEM units.

Available in 1.62:1 and 1.75:1 gear ratios and multiple shaft lengths, this lower unit supports different rigging setups commonly found on offshore and twin-engine boats requiring counter rotation.

Who It's For

This lower unit is ideal for:

• Boat owners replacing a damaged Mercury 3.0L lower unit

• Offshore or twin-engine setups needing counter rotation

• Marine repair shops servicing Mercury outboards

• Performance boaters requiring correct gear ratio matching

• Anyone upgrading from older two-piece driveshaft systems

Why This Lower Unit Is a Smart Replacement

• Built for durability in saltwater and heavy-load use

• Precision-cut gears for smoother shifting

• Cost-effective alternative to OEM assemblies

• Multiple shaft options to match different setups

• Engineered specifically for Mercury 3.0L fitment

Key Features

• Designed to replace many Mercury 3.0L outboard lower units

• Supports counter rotation configurations

• Available in 1.62:1 and 1.75:1 gear ratios

• Multiple shaft length options: 20", 25", and 30"

• 13-spline one-piece driveshaft design

• Stub shaft option for 8-spline applications

• Marine-grade housing and internal components

Technical Specifications

Compatibility Notes

• Fits many Mercury 3.0L outboards (SN 1B504989 and below)

• Does not replace Torque Master, Torque Master 2, or Sport Master

• For engines using 8-spline driveshafts, choose the stub shaft version

• If your unit serial number is below OG438000, reuse your existing water tube coupling or purchase the correct replacement part

• Users upgrading from 13-spline two-piece shafts should install the correct one-piece shaft option

Variant Explanation

13 / 1.75 / 3.0L / 20" Shaft
Best for standard 20-inch transom setups using the 1.75 gear ratio.

13 / 1.75 / 3.0L / 25" Shaft
Designed for boats requiring a longer driveshaft configuration.

13 / 1.75 / 3.0L / 30" Shaft
Used on larger offshore boats with extended shaft setups.

13 / 1.75 / 3.0L / Stub Shaft
For engines running an 8-spline driveshaft system.

13 / 1.62 / 3.0L / 20" Shaft
Optimized for applications requiring the 1.62 performance ratio.

13 / 1.62 / 3.0L / 25" Shaft
Balances performance and compatibility for mid-length shaft setups.

13 / 1.62 / 3.0L / Stub Shaft
Required for specific conversion setups.

What's Included

• Complete SE216 Lower Unit Assembly

• Pre-assembled gearcase

• Driveshaft (based on selected variant)

• Ready-to-install unit

Important Notes / Disclaimer

Always confirm:

• Engine serial number

• Shaft length

• Gear ratio

• Rotation type

before ordering to ensure proper fitment.

Professional installation is recommended for best performance and longevity.

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