Need lower unit case for a 1987 Yamaha 2 stroke 30hp longshaft, What fits?

[bluesky]

I need a lower unit case or lower unit for a 1987 Yamaha 2 stroke 30hp long shaft.
Will a range of horsepower and years lower unit cases fit this engine? I notice that the part number is different for each year and horsepower. Any help would be appreciated. Thanks