Introducing the New Aftermarket MerCruiser Complete Gearcase for Gen II Alpha One I/O drives, designed for models ranging from 1991 to the present. This complete gearcase is a high-quality, aftermarket alternative to OEM units and is built for dependable performance, smooth operation, and maximum durability. Whether you’re a weekend boater, marina technician, or performance enthusiast, this lower unit offers a cost-effective solution for replacing a damaged, worn, or outdated MerCruiser gearcase.

This gearcase is compatible with multiple engine types up to 300 HP, including popular models like the MerCruiser 4.3L, 5.0L, and other small block marine engines. Available in four gear ratios—1.47, 1.62, 1.81, and 1.94—you can select the optimal configuration for your engine and application. A counter rotation option is also available for dual-engine setups, with an additional charge of $200.

Unlike many other aftermarket units, this MerCruiser Gen 2 replacement is built to exacting standards and includes the latest features, such as compatibility with the updated speedometer fitting (OE# 860382). Note that this fitting is not included, and is required for accurate speedometer function.

In addition to reliability and smooth power transfer, this gearcase is eligible for our core rebate program, which allows you to return your old lower unit for up to $200 cash back, depending on its condition. Backed by a comprehensive 3-Year FAULT-FREE Warranty, this unit ensures peace of mind on the water.

Perfect for anyone needing a replacement MerCruiser Alpha One Gen 2 lower unit, SE116 sterndrive, or MerCruiser gearcase parts, this complete lower unit is in stock and ready to ship today.