Mercury XR4 Mag II Lower Unit | 20" Shaft | 1.87:1 Gear Ratio | Fits 1988–1991 Mercury 135HP, 150HP, 175HP & 200HP Outboards | 1-Year Warranty

Product Overview

Restore the performance and reliability of your Mercury outboard with this genuine Mercury XR4 Mag II Lower Unit, designed for select 1988–1991 Mercury 135HP, 150HP, 175HP, and 200HP outboard engines. Featuring a 20-inch shaft and 1.87:1 gear ratio, this professionally serviced OEM lower unit delivers smooth shifting, dependable power transfer, and long-lasting durability. Every lower unit is completely disassembled, carefully inspected, fully resealed, and pressure tested before shipment. A new water pump impeller is installed during servicing, while all internal components are inspected under magnification. OEM gears are retained whenever they meet Mercury factory specifications, ensuring dependable performance and extended service life. Ready for installation and backed by a 1-Year Warranty, this lower unit is an ideal replacement for worn, damaged, or failed gearcases.

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Key Features

• Genuine OEM Mercury XR4 Mag II Lower Unit
• Fits Mercury 135HP, 150HP, 175HP & 200HP Outboards
• 20-Inch Shaft
• 1.87:1 Gear Ratio
• Compatible with XR4 Mag II Applications
• Professionally Inspected
• Fully Resealed
• Pressure Tested
• New Water Pump Impeller Installed
• Internal Components Inspected Under Magnification
• OEM Gears Retained When Within Specification
• Ready for Installation
• 1-Year Warranty Included

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Technical Specifications

Specification	Details
Brand	Mercury
Product Type	Lower Unit
Condition	Professionally Serviced
Model	XR4 Mag II
Gear Ratio	1.87:1
Shaft Length	20 Inches
Horsepower	135 HP / 150 HP / 175 HP / 200 HP
Model Years	1988–1991
Driveshaft Length	21-1/4 Inches
Driveshaft Splines	8
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 outboard engines including: Model Years

• 1988
• 1989
• 1990
• 1991

Horsepower

• 135 HP
• 150 HP
• 175 HP
• 200 HP

Model

• XR4 Mag II

Shaft Length

• 20-Inch

Gear Ratio

• 1.87:1

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 thoroughly inspected before being offered for sale. Service and inspection include:

• Complete disassembly and inspection
• Internal components inspected under magnification
• Fully resealed
• Pressure tested to ensure leak-free performance
• New water pump impeller installed
• 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 XR4 Mag II 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 carefully 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 XR4 Mag II Lower Unit is backed by a 1-Year Warranty. If the lower unit experiences a covered failure during normal operation within the warranty period, EZ Boats Marine will repair, replace, or refund the item if a replacement is unavailable, in accordance with our warranty policy.

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Why Buy from EZ Boats Marine?

• Genuine OEM Mercury Marine Parts
• Professionally Serviced Lower Units
• Fully Resealed and Pressure Tested
• New Water Pump Impeller Installed
• OEM Internal Components
• Smooth Shift Operation Verified
• 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 1988–1991 Mercury 135HP, 150HP, 175HP, and 200HP outboards equipped with a 20-inch shaft and 1.87:1 gear ratio. Always verify your engine's model number, serial number, and OEM specifications before ordering.

Has this lower unit been professionally serviced?

Yes. It has been completely disassembled, inspected, fully resealed, pressure tested, and fitted with a new water pump impeller before being offered for sale.

What gear ratio does this lower unit have?

This lower unit features a 1.87:1 gear ratio, providing factory-correct performance for compatible Mercury XR4 Mag II outboards.

Is gear oil included?

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

Does this lower unit include a warranty?

Yes. This Mercury XR4 Mag II Lower Unit is backed by a 1-Year Warranty, providing added confidence and peace of mind with your purchase.