GHmarine Bellows Kit for MerCruiser Alpha One Gen 2 (1991+) — Gimbal Bearing & Gasket Set

GHmarine 803099T1 Bellows Kit is a complete transom service replacement for MerCruiser Alpha One Gen 2 stern drives, supplying exhaust, U-joint and shift cable bellows plus a gimbal bearing and installation gasket set.

If your MerCruiser Alpha One Gen 2 stern drive (1991 and newer) is showing signs of wear at the transom connection, this GHmarine kit provides the parts needed to restore the watertight, flexible joint between the engine and drive. It replaces OEM part 30-803099T1 (also referenced as Sierra 18-8206-1 or Mallory 9-72904) and bundles the common wear items technicians replace during a transom service, saving time and reducing return trips.

What exactly comes in this bellows kit and why is each piece included?

The kit groups the components most likely to degrade at the transom: the U-joint bellow, exhaust bellow and shift cable bellow protect moving parts from water and corrosion. The included gimbal bearing supports the drive’s pivoting motion while the gasket kit and 3/4" water hose make the assembly ready for a straightforward service.

• U-joint bellow — seals and flex protection for the universal joint
• Exhaust bellow — routes exhaust while keeping water out
• Shift cable bellow — protects shift linkage from spray and salt
• Gasket kit and gimbal bearing — ensures proper sealing and smooth pivot
• 3/4" water hose — replaces worn transom cooling hose

How will replacing these parts help my stern drive perform?

Fresh bellows and a new gimbal bearing reduce the risk of water intrusion into the boat and lower the chance of sudden drive failure due to a corroded joint. Replacing worn components during a transom service restores proper alignment and reduces vibration for smoother operation.

• Prevents water leaks through damaged bellows
• Reduces corrosion risk on the U-joint and internal components
• Stabilizes drive alignment and lowers vibration
• Helps maintain OEM-style sealing at the transom

Is this kit compatible with my engine and how do I confirm fit?

This kit is designed for MerCruiser Alpha One Gen 2 stern drives from 1991 onward and replaces the OEM part number 30-803099T1 (Sierra 18-8206-1 / Mallory 9-72904). If you’re unsure about fit, check your stern drive model and serial tag or contact the seller with your engine model for verification before ordering.

• Compatible with MerCruiser Alpha One Gen 2 (1991+)
• Replaces OEM 30-803099T1 and equivalent aftermarket numbers
• Confirm by matching your drive model and serial information

How difficult is installation and what should I expect during service?

Installation is a moderate job typically handled during a transom service—an experienced DIYer can complete it, but many owners prefer a marine mechanic for correct alignment and bearing replacement. The kit includes most seals and a hose needed for reassembly, but basic tools and torque procedures are required to ensure a reliable seal.

• Moderate difficulty: mechanical skill and standard tools required
• Expect to remove the drive for gimbal bearing replacement in many cases
• Included gasket kit and hose reduce the need for extra parts
• Professional service recommended for first-time installers

Who this is for: boat owners and marine technicians who operate MerCruiser Alpha One Gen 2 stern drives and want a complete transom service kit to restore sealing and joint function. It’s ideal for preventative maintenance, addressing visible bellows cracks or leaks, and for anyone replacing the gimbal bearing during routine drive service.