Can you tell if any threads are imperial or metric, this may sort out a possible origin at least.
I've got something not too dissimilar which is supposed to be for a competition tiger cub ?
Although the fore and aft tank mounts are not really the same actual shape as yours.
A comparison of c-to-c distances may be instructive ?
Your tank also seems to have tank mounts underneath at the front,
so maybe someone was hedging their bets ?
Unless they were for something to bolt up to.
