Extend the performance and versatility of your Mercury 25–30 HP 4-Stroke outboard with this Bay Manufacturing 5-inch Extension Kit. Designed only for motors using the 2-hole drill pin shift shaft coupler, this kit adds a true 5 inches of shaft length—essential for improving water displacement, propeller bite, and overall boat handling.
Spacer housings are cast from marine-grade alloy, while the kit includes stainless-steel shafts and hardware for long-lasting durability.
A 1-year manufacturer warranty is included.
Product Features
- Adds 5 inches of shaft length
- Designed for Mercury 25 & 30 HP 4-Stroke outboards (2005 & newer)
- Fits models with 2-hole drill pin shift shaft coupler
- Motor must have 5 studs and be Tohatsu-built
- Stainless-steel driveshaft, shift shaft, and studs
- Marine-grade cast extension housing
- 1-year Bay Manufacturing warranty
- Some housings ship painted black; others ship unpainted sandblasted finish
Motor Compatibility — Must Match ALL Specs
| HP | Stroke | Year | Shift Shaft Coupler |
|---|---|---|---|
| 25, 30 | 4 | 2005 & Newer | 2-hole drill pin |
Important Fit Notes:
- If your shift shaft has a threaded end, you need Kit 303A, not this kit.
- Motor must have 5 studs on the housing.
- Motor must be a Tohatsu-manufactured Mercury.
- Compatible with 0R-series serial numbers.
Parts Included
- (1) 5" Extension Housing
- (1) 5" Driveshaft
- (1) 5" Shift Shaft
- (1) 5" Water Tube
- (3) Studs & Nuts
- (1) Bushing
Additional Information
This kit adds 5 inches of shaft length for improved control and reduced cavitation.
Bay Manufacturing extension kits are known for high durability and precise OEM-level fitment.
Not returnable except for warranty claims.
Shipping Information
Additional shipping fees to Alaska, Hawaii, U.S. Territories, or international destinations will be calculated after checkout.
You will receive a PayPal request for any additional charges.
(Some items may be excluded from international shipping.)
Customer Support
For questions or to confirm compatibility, please email customerservice@marinepartswarehouse.com
Please include your engine model or serial number to help confirm proper fitment before ordering.
