Mercruiser New Alpha I Lower Unit/Gearcase

New MerCruiser Alpha One Lower Unit – Compatible with Alpha I Outdrives (1972–1990) – Aftermarket Replacement Gearcase

This brand-new mercruiser alpha one lower unit is designed as a direct-fit replacement for the MerCruiser Alpha I (Gen 1) sterndrive units manufactured between 1972 and 1990. Built to deliver reliable performance, this lower unit is ideal for replacing damaged or worn gearcases on 3.0L and 4.3L MerCruiser Alpha One inboard/outboard engines.

Compatible with models using Alpha One Gen 1 drives, it features the proper housing dimensions and gear ratios to ensure proper fit and function. Whether you’re restoring your Alpha 1 lower unit, maintaining a MerCruiser 3.0, or repairing a 4.3L outdrive, this gearcase is an excellent solution — reliable, efficient, and cost-effective.

Finished in durable black, this unit is non-OEM, not remanufactured, and comes ready for installation. It does not include the upper driveshaft, shift shaft, or water pump — you must transfer those from your existing unit.

Pricing

Total Price: $1,065
Less $200 Core Reabte
Final Price: $865

Product Finish:

• 100% brand-new aftermarket (non-OEM)
• Smooth black finish
• Not remanufactured

Core Reabte Information

• Return your old core, get up to $200 back
• Rebate amount will vary based on the condition of your core
• ♻️ Recycle your core- keep boat parts out of the landfill

Useful Resources

• 🔍 How to find your Boat Engine serial number? 
• Still deciding? Watch our YouTube video How to avoid common lower unit replacement mistakes
• To help extend the life of your gearcase, check out our Boat Maintenance Checklist