Shelby long tank frames

[nightrider]

There was a post about straight bar, hanging tank Shelby's. Inquiring about how many are out there.
This got me thinking:
Most of the long tank frames I've seen have a straight down tube. Mine has a curved down tube. Was not badged a Shelby though, it's a Road King. I have came across one other with the curved down tube in the archives.
So... How many long tank frames, with a curved down tube are out there? Any idea what years they were?
Here's mine ( tank not attached).

 

[prewarmachine]

I have one with the curved down tube, no badge. My Shelby enthusiast friend told me it was probably a post war Hiawatha badged bike. I'll try to put up a picture later.