Mercury Counter Rotation Lower Unit | 30" CXXL Shaft | 1.75:1 Gear Ratio | Fits 1999 & Up Mercury Optimax & Pro XS 200HP, 225HP & 250HP V6 Outboards | Genuine OEM

Product Overview

Upgrade or replace your twin-engine setup with this genuine OEM Mercury Counter Rotation Lower Unit, designed for select 1999 and newer Mercury Optimax and Pro XS 200HP, 225HP, and 250HP 3.0L V6 outboards. Featuring a 30-inch CXXL shaft, 1.75:1 gear ratio, and left-hand counter rotation, this factory Mercury lower unit delivers the durability, precision, and performance expected from original equipment. This is a brand-new, never-installed OEM Mercury lower unit. Although it is not supplied in the original Mercury packaging, the unit itself is new, complete, and professionally inspected prior to listing to ensure excellent condition. Designed specifically for port-side twin-engine applications, this counter-rotation lower unit provides smooth shifting, reliable power transfer, and factory-correct performance for Mercury Optimax and Pro XS outboards.

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Key Features

• Genuine OEM Mercury Lower Unit
• Brand New – Never Installed
• 30-Inch CXXL Shaft
• Left-Hand Counter Rotation
• 1.75:1 Gear Ratio
• Fits Mercury Optimax & Pro XS V6 Outboards
• Compatible with 200HP, 225HP & 250HP Engines
• Professionally Inspected
• Ready for Installation
• Ideal for Twin-Engine Applications

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Technical Specifications

Specification	Details
Brand	Mercury
Product Type	Counter Rotation Lower Unit
Condition	New
OEM Part Number	880686A53
Mercury Assembly Number	1600-880686A53
Shaft Length	30 Inches (CXXL)
Rotation	Left-Hand Counter Rotation
Gear Ratio	1.75:1
Driveshaft Splines	13
Propeller Shaft Splines	15
Pinion Teeth	12
Color	Black

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OEM Part Numbers

Current Part Number

• 880686A53

Mercury Assembly Number

• 1600-880686A53

Supersedes

• 880686T39
• 880686A43
• 880686T29

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Compatible Applications

Designed for select Mercury outboard engines including: Model Years

• 1999 and newer

Horsepower

• 200 HP
• 225 HP
• 250 HP

Engine Type

• Mercury Optimax 3.0L V6
• Mercury Pro XS 3.0L V6

Shaft Length

• 30-Inch CXXL

Gear Ratio

• 1.75:1

Rotation

• Left-Hand Counter Rotation (Port Engine)

Compatible Serial Number

• 1B504989 and above

Important: Always verify your engine's model number, serial number, shaft length, gear ratio, and OEM part number before purchasing. Mercury lower units are serial-number specific within the 3.0L platform. If you need assistance confirming compatibility, our team is happy to help before you order.

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Condition

This is a genuine OEM Mercury lower unit that has never been installed. Inspection highlights include:

• Brand new OEM Mercury component
• Never installed
• Complete assembly
• Professionally inspected prior to listing
• Not shipped in the original Mercury box
• Ready for installation

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What's Included

Your purchase includes:

• Mercury Counter Rotation Lower Unit Assembly
• Factory-installed internal components

Only the components shown in the product photos are included.

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Shipping Information

Every lower unit is securely packaged to protect it during shipping. We offer fast shipping throughout the United States, with international shipping available upon request. For an accurate shipping quote, please provide:

• Country
• ZIP or Postal Code
• Commercial or Residential Address
• Whether liftgate service is required

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Why Buy from EZ Boats Marine?

• Genuine OEM Mercury Marine Parts
• Brand New Mercury Components
• Factory Performance and Reliability
• Professionally Inspected Before Shipment
• Ideal for Repower and Twin-Engine Applications
• Secure Packaging
• Fast Nationwide and International Shipping
• Experienced Marine Customer Support

EZ Boats Marine is committed to supplying premium OEM marine parts backed by dependable service, expert support, and honest product descriptions.

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Frequently Asked Questions

Which Mercury outboards does this lower unit fit?

This lower unit fits select 1999 and newer Mercury Optimax and Pro XS 3.0L V6 200HP, 225HP, and 250HP outboards equipped with a 30-inch CXXL shaft and 1.75:1 gear ratio. Always verify your engine's serial number and OEM part number before ordering.

Is this a new OEM Mercury lower unit?

Yes. This is a genuine OEM Mercury lower unit that is brand new, has never been installed, and has been professionally inspected before listing.

Does this fit a single-engine boat?

This is a left-hand counter-rotation lower unit, typically used on the port engine of twin-engine installations. Verify your engine's rotation before purchasing.

Does it come in the original Mercury box?

No. Although this lower unit is brand new and genuine OEM Mercury, it is not shipped in the original Mercury packaging.

Is this lower unit ready to install?

Yes. The unit is complete, professionally inspected, and ready for installation on a compatible Mercury Optimax or Pro XS outboard.