Ah, so, no definitive answer, no concrete proof, no way to properly disclaim that this is in fact what it is, Yugoslavian prototype. Not to mention not having the resources for proper research, or having lack of knowledge of the other prototypes.
And then casting the ball to me, to find the photo of an empty box.
Quite nice.
No, prove me and any other author worth its salt wrong. Prove the man who actually took those orders from IKOM wrong.
Find the data, from the beginning, this is where I will give a hint, which is in Jajce, in november 1943.
Secondly, who was the first producer of the said order?
Thirdly, could the accepted model be a second prototype variant, presented upon the committee which then chose the better looking one?
I wish you good fortune in the arduous labor to come.