Help with fuel tank identification

[Bob_Matthews]

Here is the tank that came with my Mototrans Elite 200, but I'm not sure if it's original (or even a Ducati tank).
The tank fits the frame quite well but seems it would need a fairly tall rear rubber mount to keep the tank off the frame.
The filler cap arrangement also seems quite unusual?

Any ideas if it could be original, or if not what bike it might have come from?

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