I have come into possession of a Canon rangefinder but I'm not sure what model it is. On the basis of various clues, including the shutter speeds available and the serial number, I know it is either a IIS2 or a IID2, but I can't tell which one. Is there some way to distinguish between these two?
According to this page, the IID2 has no flash capacity, while the IIS2 does.
Hope it helps.