For some reason I thought it was a '14, probably because it came from a pile of '14 parts I bought a few decades ago. It does have a pot metal cap which may or may not be original. I can't recall anything about a pot metal gas caps. Anyone have any ideas? I finally got that miserably stuck cap out and found the inside of the tank to be perfectly clean and all still galvanized with only the faintest trace of tiny rust discolorations here and there. No debris or gunk at all; just perfectly clean inside and out. I am building a hack body for my 27 so I'll need this frame mounted tank under the seat. Fired up the 27 today for the first time since I got it and it purred like a baby kitten.