This statement made me think it might not be crank bearings:

"However, the seriously audible moment is immediately after the engine is shut off. The whistles are quite pronounced (loud and long)."

If the whistles are there after engine is shut off, how can it be crank bearings if the crank is not in use?

I hear whistles after shutting off the engine (35d) or when turning on ignition, but those are (I assume) electirc pumps and other equipment. Does not sound like "airy"..