Just as a guess, I would bet there were more of these little motors made than anything else in the toy field! They powered a few early slot cars, but they were also on untold numbers of motorized toys of all types! They're basically 3V motors so should run pretty good on 12V - at least for a little while.
I think they were about 99 cents at the time, maybe 79, so that was cheap even at the time!
Don