Mercury Optimax Lower Unit | 25" Shaft | 2.07:1 Gear Ratio | Fits 2004 & Newer Mercury Optimax 75HP, 90HP & 115HP Outboards | 1-Year Warranty

Product Overview

Restore the performance and reliability of your Mercury outboard with this genuine Mercury Optimax Lower Unit, designed for select 2004 and newer Mercury Optimax 75HP, 90HP, and 115HP outboard engines. Featuring a 25-inch shaft and 2.07:1 gear ratio, this professionally serviced lower unit is an ideal replacement for damaged or worn gearcases. Every lower unit is thoroughly inspected, resealed, and pressure tested before shipment to ensure dependable performance. The unit is fitted with a new water pump impeller, while the driveshaft and prop shaft are checked for straightness, and the shift mechanism is tested to verify smooth gear engagement. Built using genuine OEM Mercury components whenever possible, this lower unit is ready for installation and backed by a 1-Year Warranty for added confidence.

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Key Features

• Genuine OEM Mercury Optimax Lower Unit
• Fits Mercury Optimax 75HP, 90HP & 115HP Outboards
• 25-Inch Shaft
• 2.07:1 Gear Ratio
• Professionally Resealed
• Pressure Tested
• New Water Pump Impeller Installed
• Driveshaft and Prop Shaft Checked for Straightness
• Shift Operation Tested
• Ready for Installation
• 1-Year Warranty Included

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Technical Specifications

Specification	Details
Brand	Mercury
Product Type	Lower Unit
Condition	Professionally Serviced
Engine Compatibility	Mercury Optimax
Horsepower	75 HP / 90 HP / 115 HP
Model Years	2004 and Newer
Shaft Length	25 Inches
Gear Ratio	2.07:1
Driveshaft Length	27-1/4 Inches
Driveshaft Splines	13
Prop Shaft Splines	15

Driveshaft length is measured from the top of the water pump to the top of the driveshaft.

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Compatible Applications

Designed for select Mercury Optimax outboard engines including: Model Years

• 2004 and Newer

Horsepower

• 75 HP
• 90 HP
• 115 HP

Shaft Length

• 25-Inch (Extra Long)

Gear Ratio

• 2.07:1

Important: Always verify your engine's model number, serial number, shaft length, gear ratio, and OEM part number before purchasing. If you need assistance confirming compatibility, our team is happy to help.

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Condition

This lower unit has been professionally serviced and inspected to ensure reliable operation. Service and inspection include:

• Complete reseal
• Pressure tested for leak-free performance
• New water pump impeller installed
• Driveshaft checked for straightness
• Prop shaft checked for straightness
• Shift operation tested through all gears
• Internal components inspected
• OEM gears retained when they meet factory specifications
• Ready for installation

Please Note: Gear oil is not included and must be added before operating the lower unit.

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What's Included

Your purchase includes:

• Mercury Optimax Lower Unit Assembly
• New Water Pump Impeller
• Professionally Resealed and Pressure-Tested Gearcase

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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Warranty

This Mercury Optimax Lower Unit is backed by a 1-Year Warranty. Warranty coverage is activated by returning your old lower unit core. A prepaid return shipping label will be provided for qualifying core returns. A valid core must:

• Have an intact gearcase housing
• Have rotating driveshaft and prop shaft
• Be free from major structural damage

If you do not have a qualifying core, please contact EZ Boats Marine to discuss available warranty options.

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Why Buy from EZ Boats Marine?

• Genuine OEM Mercury Marine Parts
• Professionally Serviced Lower Units
• Pressure Tested for Leak-Free Performance
• New Water Pump Impeller Installed
• OEM Internal Components
• 1-Year Warranty Included
• Secure Packaging
• Fast Nationwide and International Shipping
• Experienced Marine Customer Support

EZ Boats Marine is committed to supplying premium OEM marine components backed by dependable service, expert support, and reliable performance.

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Frequently Asked Questions

Which Mercury outboards does this lower unit fit?

This lower unit fits select 2004 and newer Mercury Optimax 75HP, 90HP, and 115HP outboards equipped with a 25-inch shaft and 2.07:1 gear ratio. Always verify your engine's model number, serial number, and OEM specifications before ordering.

Has this lower unit been serviced?

Yes. It has been professionally resealed, pressure tested, fitted with a new water pump impeller, and inspected to ensure reliable operation.

What is the gear ratio?

This lower unit features a 2.07:1 gear ratio.

Is gear oil included?

No. Gear lubricant is not included and should be added before the lower unit is placed into service.

Does this lower unit include a warranty?

Yes. This lower unit is backed by a 1-Year Warranty, subject to the return of a qualifying core in accordance with EZ Boats Marine's warranty policy.