Extend your Mercury outboard from a 15" to a 20" shaft with this premium Bay Manufacturing 5" Extension Kit. Designed for 25–50 HP 4-stroke Mercury engines, this kit offers a direct bolt-on solution and includes every component required to properly extend the driveshaft housing, shift shaft, and water tube.
Each kit is built with stainless steel shafts and studs, and the spacer housing is cast from the same alloy series used in Mercury outboards for exceptional durability. Some kits arrive painted black, while others feature a clean, sandblasted unpainted finish.
Product Features
- Adds 5 inches of extension to your Mercury outboard
- Compatible with select 25–50 HP 4-stroke models
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Includes all major components:
- 5" extension housing
- 5" drive shaft
- 5" shift shaft
- 5" water tube
- Studs, nuts, and bushing
- Precision-machined stainless steel shafts and studs
- Designed for OEM-grade fitment and longevity
- Motor Compatibility Requirements
- Your engine must match all listed specifications to ensure correct fitment.
- Compatible Serial Numbers
- 0G760300 and Up (25–50 HP)
- 0T425933 and Up (25 HP)
- 1B184725 and Up (25 HP)
- Compatibility by HP & Year
- 2004 and Older
- 25 HP 4-Stroke
- 30 HP 4-Stroke
- Additional Models
- 40 HP 4-Stroke
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50 HP 4-Stroke – 3 Cylinder
- Housing must measure 11 ¾ inches
- Size & Finish
- Adds 5 inches of shaft length
- Finish: Unpainted sandblasted (may vary)
- Can be painted any color
- Manufacturer
- Bay Manufacturing – industry leader in outboard extension components
- Additional Information
- These extension kits are not eligible for return except in cases of warranty claim—please confirm your exact motor specifications before ordering.
- A 1-year warranty is included.
Shipping Information
Additional shipping fees to Alaska, Hawaii, U.S. Territories, or international destinations will be calculated after checkout.
A PayPal request will be emailed 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.
