New SEI Gearcases – Mercury/Mariner 6-Cylinder Lower Units

New SEI (Sterndrive Engineering) Mercury & Mariner V6 Replacement Outboard Gearcases

Explore our selection of brand‑new SEI aftermarket lower unit gearcases explicitly designed for Mercury and Mariner six‑cylinder outboard engines. These gearcases deliver reliable, performance‑driven solutions with precise engineering tailored for V6 configurations. These replacements offer seamless installation, durability, and a three-year fault-free warranty.

SEI

New SEI / Mercury 4/6-Cylinder 3.0L/2.6L/1.7L Counter Rotation Outboard Gearcases

MSRP:

Was:

Now: $1,865.00

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SEI

New SEI / Mercury 4/6-Cylinder 3.0L/2.6L/1.7L Fleetmaster & Verado Gearcase

MSRP:

Was:

Now: $1,645.00

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SEI

New SEI / Mercury 1979-2018 150, 175, 200 HP 2.0/2.4/2.5L Gearcase

MSRP:

Was:

Now: $1,195.00

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SEI

New SEI / Mercury 1994-2018 V6 200/225/250 HP 3.0L Gearcase

MSRP:

Was:

Now: $1,195.00

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SEI

New SEI / Mercury 1994-2018 200/225/250 HP 3.0L V6 Counter Rotation Gearcase

MSRP:

Was:

Now: $1,395.00

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SEI

New SEI / Mercury 4/6-Cylinder 3.0L/2.6L/1.7L Counter Rotation Outboard Gearcases

This listing is for a New SEI Counter Rotation Outboard Gearcases compatible with Mercury engines. This gearcase includes a 3-Year Warranty from the manufacturer. Click here for info ---> SEI Marine Warranty Info The SE228 is...

MSRP:

Was:

Now: $1,865.00

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SEI

New SEI / Mercury 4/6-Cylinder 3.0L/2.6L/1.7L Fleetmaster & Verado Gearcase

This listing is for a New SEI / Mercury 4/6-Cylinder 3.0L/2.6L/1.7L Fleetmaster & Verado Gearcase. The 221 gearcases fit three different types of engines. They are as follows: - 3.0 Liter – V6 – Two Stroke (13...

MSRP:

Was:

Now: $1,645.00

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SEI

New SEI / Mercury 1979-2018 150, 175, 200 HP 2.0/2.4/2.5L Gearcase

Restore optimal performance of your Mercury V6 outboard with the New SEI / Mercury 1979-2018 150, 165, 200 HP 2.0/2.4/2.5L Gearcase. Built with a durable plastic water pump and a standard 4 ¾” bullet, this is a direct replacement of standard...

MSRP:

Was:

Now: $1,195.00

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SEI

New SEI / Mercury 1994-2018 V6 200/225/250 HP 3.0L Gearcase

Upgrade the Mercury outboard with the brand-new SEI/Mercury gearcase. It is designed for 1994-2018 V6 200, 225, and 250 HP 3.0L engines. The model is for 8- and 13-spline driveshafts, providing flexibility for various engine configurations. The New SEI...

MSRP:

Was:

Now: $1,195.00

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SEI

New SEI / Mercury 1994-2018 200/225/250 HP 3.0L V6 Counter Rotation Gearcase

This listing is for a New Sterndrive Engineering Mercury 3.0L Counter Rotation Gearcase. These models use a metal water pump and have dual-water pick ups.. This unit has models for both 8- and 13-spline driveshafts When replacing a unit with an 8-spline...

MSRP:

Was:

Now: $1,395.00

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New SEI (Sterndrive Engineering) Mercury & Mariner V6 Replacement Outboard Gearcases

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