This one came from Italy, so maybe it's more common in Europe, but it's one I don't think I've seen before. I mean, I've seen a lot by now, so maybe I've forgotten, but I don't think so! Anyway, the motor appears to basically be the same height and width as a 16D, but the length is way shorter and is the same as a modern PS4002. The end bell makes me think it's a Johnson, as I've seen the same end bell marking on Johnsons. Speaking of the end bell, it's such a good copy of a Mabuchi that it even has "The Mabuchi Crack" It's also the early style where the brushes ride directly on the plastic, and they are some teensy-weensy brushes, so right away it's clear the end bell will need some pretty major reworking.
The can has a large brass bushing carrier with an odd "key" cast into one side of it that was probably used for locating the motor in whatever it was originally made to fit in. I won't know until I open her up, but that all may have to change as well, but maybe it can be kept and only modified internally.
The arm is a very short stack (as you would guess) and the motor is functional as it stands. At full tilt boogie, the motor draws like three tenths of an amp ( ), so whatever it "powered" must have been pretty slow. I'm guessing it was some sort of homeset car, and that kind of "performance" was probably entirely appropriate. Anyhow, "I'm going in"!