Upgrade your Mercury 8–9.9 HP outboard with this Bay Manufacturing 5-inch Extension Kit designed specifically for 10-spline driveshaft Pro Kicker and Big Foot models. This kit provides a precise long-shaft conversion that improves handling, propeller bite, and overall performance. Spacer housings are cast from the same marine-grade alloy used by major outboard manufacturers, ensuring long-term durability.
This kit includes all required components—driveshaft, shift shaft, water tube, and hardware—making installation straightforward and reliable. A 1-year manufacturer warranty is included.
Product Features
- Adds 5 inches of shaft length
- Designed for Mercury 8 & 9.9 HP 4-Stroke (Big Foot & Pro Kicker models)
- Fits 10-spline driveshaft engines only
- Precision-machined stainless-steel shafts and hardware
- Marine-grade cast alloy extension housing
- Compatible with 0R-and-newer Mercury serial numbers
- Some housings ship black-painted; others ship unpainted sandblasted finish
- Includes 1-year Bay Manufacturing warranty
Motor Compatibility — Must Match All Specs
Mercury 4-Stroke (10-Spline Pro Kicker):
| HP | Stroke | Year | Model | Splines | Serial Range |
|---|---|---|---|---|---|
| 9.9 | 4 | 2005–Present | Pro Kicker | 10 splines | 0R052328 & Up |
Important:
- If your driveshaft has 11 splines, you need Kit 302, not 302A.
- Must have 8mm cap bolt thread and no dowel pins.
Parts Included
- (1) 5" Extension Housing
- (1) 5" Driveshaft (10-Spline)
- (1) 5" Shift Shaft
- (1) 5" Water Tube
- (3) Studs & Nuts
- (1) Bushing
Additional Information
Compatible with:
- Mercury 8 & 9.9 HP Big Foot
- Mercury 8 & 9.9 HP Pro Kicker
Ideal for converting short-shaft motors to long-shaft for improved thrust and reduced cavitation.
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.
