I showed mine to a guy last week who said he rented from the original owner and had lots of chances to buy it from him cheap years ago. He was shocked that it's special. Only the guy that stored it for years in his shop knew what it was, apparently he didn't tell anyone. Except me.
I also know the guy that assembled it new from the crate, it was the first one sold here and red. He still owns the blue/green second one and he assembled it in January of 70, just before he went into the army.