This SEI Marine Upper Gear Set is a direct replacement for MerCruiser Type I, R, MR, and Alpha One sterndrives from 1972 to 1990, designed for 4.3L V6 engines.
Featuring a 1.81 gear ratio, this set provides smooth, reliable power transfer and efficient upper drive performance under all marine conditions.
It replaces OEM 43-75325A3 and also fits Gen II drives (Serial #0K999999 and below).
Manufactured to OEM standards from high-strength marine-grade materials, this SEI gear set ensures durability, precision, and long-term dependability — all backed by SEI’s 3-Year Fault-Free Warranty.
Product Features
- Direct OEM Replacement: Replaces MerCruiser OE# 43-75325A3
- Fitment: MerCruiser Type I, R, MR, and Alpha One drives (1973–1990)
- Additional Fitment: Gen II drives (Serial #0K999999 and below)
- Engine Compatibility: 4.3L V6 models
- Gear Ratio: 1.81
- Condition: 100% brand-new SEI Marine replacement gear set
- Warranty: 3-Year Fault-Free Warranty provided by SEI Marine
Additional Information
Note: Designed for 4.3L V6-powered MerCruiser applications using the 1.81 ratio gear configuration.
All parts required for a complete upper gear housing rebuild are available upon request.
If you need additional drive components, please email or fill out the contact form and we’ll assist you in locating everything needed.
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.
