30-803099T1 Alpha One Gen II Transom Seal Kit · Fits MerCruiser Alpha One Gen II select 1991+, Replaces 18-8206-1, 18-8218, 21960

30-803099T1 Alpha One Gen II Transom Seal Kit · Fits MerCruiser Alpha One Gen II select 1991+, Replaces 18-8206-1, 18-8218, 21960

GHMarine Alpha One Gen II transom seal / service kit — CSKU 23BK211 — for select MerCruiser Alpha One Gen II sterndrives (about 1991+). Primary OEM 30-803099T1. Cross-refs 18-8206-1, 18-8218, 21960, 9-72900, 9-72904, 68399P. This is a full Gen II overhaul kit — not Gen I (30-803097T1), not Bravo (30-803100T1), and not the Gen II rubber-only three-bellow pack (GH 18BK003).

Sister full-kit CSKU 17B3007 also lists 30-803099T1 — match the CSKU / carton you stock. Need Gen I kit → GH 17B3005 / 23BK210. Need Bravo kit → GH 18B5001 / 23BK209.

Which kit is this?

It is the Gen II transom seal service kit used when you pull the drive for a one-time bellows / bearing / hose / gasket refresh on listed Alpha One Gen II packages. Confirm the old kit or EPC shows 30-803099T1 — and confirm Gen II, not Gen I.

It is not Alpha One Gen I kit 30-803097T1, not Bravo / Blackhawk kit 30-803100T1, not rubber-only Gen II three-pack (GH 18BK003), and not a single bellow sold alone.

Signs yours is due

• Alpha One Gen II (1991+) transom bellows, hose, or gimbal bearing are due together and the chart calls for 30-803099T1 / 18-8206-1 / 18-8218.
• You almost ordered Gen I because an old title said "Alpha One" without Gen II — stop; wrong generation is a common buy-error on this kit.
• You only need the three rubber bellows — divert to GH 18BK003 instead of this full service kit.
• Divert: Gen I → GH 17B3005 / 23BK210. Bravo → GH 18B5001 / 23BK209. Sister full Gen II kit → GH 17B3007.

Will it fit my drive?

This kit is Compatible with select MerCruiser Alpha One Gen II sterndrives about 1991+ that specify 30-803099T1. Confirm Gen II identity and serial / EPC — not HP and not a bare "Alpha One" badge. Alpha One Gen I and Bravo / Blackhawk are not this page. Packaging cross-refs 18-8206-1 vs 18-8218 and 9-72900 (~1991–1997) vs 9-72904 (1998+ greaseable) are bearing/BOM variants — match carton.

*Final fit = OEM 30-803099T1 on EPC / old kit + Gen II confirmation. Do not order Gen I 30-803097T1 from this page.

OEM & swap numbers

Primary OEM 30-803099T1. Cross-refs 18-8206-1, 18-8218, 21960, 9-72900, 9-72904, 68399P. Catalog core examples (verify carton — revisions exist): U-joint bellow 816431A1 (Gen II flat), exhaust bellow 8M0124227 (legacy family 18654A1 / 32734A3 — not two exhaust bellows), gimbal bearing current path 30-8M2010910 (legacy 30-60794A4 / 30-60794A2 — not two bearings), water hose 32-8M0109048 (legacy 32-41725-33 — not two hoses), drive gasket current path 27-8M0091545.

Wrong part? Read before you order

• NOT Alpha Gen I kit 30-803097T1 (GH 17B3005 / 23BK210)
• NOT Bravo / Blackhawk kit 30-803100T1 (GH 18B5001 / 23BK209)
• NOT rubber-only Gen II three-pack (GH 18BK003)
• NOT two exhaust bellows or two bearings from legacy+current numbers counted twice
• NOT a title that says Gen I for this OEM — Gen II only

What ships in the box

• 1 × Alpha One Gen II transom seal / service kit (30-803099T1 path)
• Typical catalog contents when your carton matches: U-joint bellow, exhaust bellow, gimbal bearing, water hose, drive gasket, clamps/hardware as packed
• Exact child OEM revisions (18-8206-1 vs 18-8218; 9-72900 vs 9-72904; current vs legacy bearing/hose) follow the carton — count before you sell

Often ordered with related SKUs

• Sister full Gen II kit → GH 17B3007
• Gen II rubber-only three-pack → GH 18BK003
• Alpha Gen I kit → GH 17B3005 / 23BK210
• Bravo kit → GH 18B5001 / 23BK209
• Gen II U-joint bellow alone → GH 17B1007
• Exhaust bellow alone → GH 17B1003

Install tips on the Gen II transom kit

Full Alpha One Gen II transom overhaul. Cold engine; disconnect battery; support and remove the drive per the service manual. Confirm Gen II before you open the kit.

1. Confirm OEM 30-803099T1 and Gen II identity (not Gen I / Bravo) before opening the kit.
2. Photograph orientation of each bellow, hose, bearing, and gasket; compare carton contents to your drive.
3. Remove the drive and replace kit items in the Gen II service-manual order.
4. Use adhesives / expanders only where the Gen II service manual requires them for that bellow (U-joint 816431A1 is the flat Gen II style).
5. Reassemble, then check for water leaks before returning the boat to service.

FAQ

Is this Gen I?

No. 23BK211 is Alpha One Gen II 30-803099T1. Gen I is 30-803097T1. Old titles that said Gen I for this OEM were wrong.

Is 23BK211 the same as 17B3007?

Same primary full-kit OEM. This page is CSKU 23BK211 — match the CSKU / carton.

Is this the same as 18BK003?

No. 18BK003 is the Gen II rubber-only three-bellow pack. 23BK211 is the fuller service kit path.

18-8206-1 vs 18-8218 — which one?

Bearing / BOM packaging variants. Match what your carton and EPC expect — do not assume they are identical packs.

Do legacy and current bearing numbers both ship?

No. Count one bearing path (current or legacy revision) — not both numbers as two bearings.

"Alpha One" badge alone enough?

No. Confirm Gen II + OEM 30-803099T1 on serial / EPC.

Please note

Aftermarket replacement by GHMarine. Not affiliated with engine manufacturers named above. "Compatible with", "Replaces", and cross-ref numbers identify the 30-803099T1 Alpha One Gen II transom seal kit family — always confirm OEM number, Gen II (not Gen I), serial/EPC, CSKU, and carton contents before ordering.