Re: Tank frame bicycles
Two top tubes and a down tube plus the seat tube for the front triangle would be my guess. I think that is a distinction between a vintage cruiser and my hydro formed aluminum Felt in that the new bike is "inspired by" the vintage bike. I really feel connected to my bike. I should as many hours as I spend on it but there is a real difference to me between vintage and new. I just don't have the skill set to make a vintage frame reliable.
It's interesting that the empty tank bugged you. I'm not much younger (born in '59) and I remember VaRoom engines, wheelie bars, exhaust pipes, sirens and worthless plastic crash helmets. Then there was the big slicks as if a skinny eight year old was going to have trouble keeping the rubber hooked up to the pavement. How about cheater slicks so that we were "legal"? All pretty funny in retrospect but seriously cool at the time.