I was just going through a bunch of vintage Mountain Troops snowshoes stamped "Hasbro(R), Japan" (probably two dozen) and noticed just a couple of them had a number stamp on the heel of the foot platform. I enclosed a photo of one that had the number "1" stamped. I also found a "2" and "3". Most of the snowshoes had no marking at all. Are these a first issue version or a later version?