This SEI Marine Lower Gear Set is a precision-built replacement for MerCruiser Alpha One and Alpha One Gen II sterndrives with serial numbers 0F680000 and up.
Featuring a 1.62:1 gear ratio and 3.265" O.D. forward gear bearing, this set ensures smooth gear operation, quiet performance, and long-lasting durability.
It replaces OEM 828072A3, 828073A1, and 43-878087A4, providing a direct-fit solution for a variety of later-model MerCruiser applications.
This gear set is also compatible with 3.0L Mercury outboard units with 1.62 / 1.64:1 ratios (3.265" diameter forward bearing only).
Manufactured to OEM standards and backed by SEI’s 3-Year Fault-Free Warranty, this gear set is designed for optimal marine performance and longevity.
Product Features
- Direct OEM Replacement: Replaces MerCruiser OE# 828072A3, 828073A1, and 43-878087A4
- Fitment: MerCruiser Alpha I and Alpha I Gen II (1972–1997)
- Serial Range: Fits Alpha I units with serial numbers 0F680000 and up
- Engine Compatibility: Also fits 3.0L Mercury outboards with 1.62 / 1.64:1 ratios (3.265" forward bearing only)
- Gear Ratio: 1.62:1
- Bearing Size: Includes 3.265" O.D. forward gear bearing
- Construction: Marine-grade precision gears for smooth operation and durability
- Condition: 100% brand-new SEI Marine replacement gear set
- Warranty: 3-Year Fault-Free Warranty provided by SEI Marine
Additional Information
Note: This gear set includes the 3.265" O.D. forward gear bearing and is designed for later-model Alpha One / Gen II drives with serial numbers 0F680000 and up.
If you require the earlier version (3.500" O.D. bearing), please see part numbers 43-878087A4 / 43-828073A1.
If you need assistance identifying the correct gear set for your drive, please email or fill out the contact form and we will assist you.
Shipping Information
SHIPPING: Additional shipping fees to Alaska, Hawaii, U.S. Territories, or international destinations will be calculated after checkout.
You will receive an email and a PayPal money request for the additional shipping charges at the email address provided.
(Some items are excluded from international shipping.)
Customer Support
For questions or to confirm compatibility, please email customerservice@marinepartswarehouse.com .
Please include your engine model number to help confirm proper fitment before ordering.
