CM Transom Bellow Kit for MerCruiser Alpha One Gen 1 (1977–1990) — Complete Bellows, Gimbal Bearing & Hoses

Complete transom bellows replacement kit engineered to refresh the gimbal housing, U-joint, exhaust and shift bellows, hoses, clamps and gimbal bearing on MerCruiser Alpha One Gen 1 sterndrives (fits 1977–1990 models).

If your sterndrive has been in service for years, dried or cracked bellows, leaking exhaust boots or a worn gimbal bearing can invite water into the boat’s inner transom and damage steering and drive components. The CM 803097T1 kit supplies every rubber part and the gimbal bearing needed to restore the transom seal and mechanical articulation for the MerCruiser Alpha One and related R/MR models across the 1977–1990 production window.

Which MerCruiser models and serial ranges does this kit fit?

This aftermarket kit replaces the OEM 30-803097T and fits Alpha One Gen 1 sterndrives plus many R and MR variants. It is intended for MerCruiser units produced between 1977 and 1990 and matches the documented serial ranges for late-model Alpha One units.

• Designed for MerCruiser Alpha One, R and MR sterndrives
• Compatible with Alpha One SS (1986–1989) and Alpha One (1983–1990) serial ranges indicated by OEM notes
• Cross-references Sierra 18-2601-1 and GLM 21950 where applicable

What parts are included, and what OEM pieces do they replace?

The CM kit is comprehensive: it supplies U-joint and exhaust bellows, shift bellows, both sizes of water hoses, stainless clamps, a gimbal bearing and a full gasket set. Each component replaces a specific MerCruiser OEM part so you can address all common transom-service wear points in one service session.

• U-joint bellows — replaces OE 60932A4
• Exhaust bellows — replaces OE 32734A3 and 18654A1
• Water hoses — 5/8" and 3/4" hoses replace OE 32-32461 and 32-41725
• Shift bellows, gimbal bearing, gasket set and all stainless hose clamps included

What materials and build quality should I expect?

CM uses marine-grade rubber for the bellows to resist salt and sun exposure and stainless steel for the clamps to reduce corrosion at hose connections. The gimbal bearing and gasket materials are specified to match the sealing and load characteristics required by the original design.

• Marine-grade rubber bellows for UV and water resistance
• Stainless-steel hose clamps to minimize corrosion
• Gimbal bearing supplied to replace worn-or-damaged original unit
• Complete gasket set for reliable sealing during reassembly

How will installing this kit affect maintenance and drive performance?

Replacing degraded bellows and the gimbal bearing restores watertight protection of the transom area and improves steering and driveline reliability by eliminating play and leakage. Routine replacement of these parts during service helps prevent costly internal transom corrosion and drive failures later on.

• Reinstates a tight transom seal to block water intrusion
• Eliminates slack or wobble from a worn gimbal bearing
• Refreshes exhaust and shift bellows for smoother operation
• Simplifies future maintenance by replacing all wear items at once

Who is this for: The CM 803097T1 Transom Bellows Kit is aimed at boat owners, marine technicians and restoration shops working on MerCruiser Alpha One Gen 1, R or MR sterndrives from the late 1970s through 1990. If you’re performing a transom service, addressing leaks at the gimbal housing, or preparing a classic sterndrive for reliable use, this kit supplies the correct replacement rubber components, hoses, bearing and hardware to complete the job in a single overhaul.