I think all 6139 Speedtimer (Japanese Domestic Market) models have the 21J movement. I have a couple of these and I would suggest that they are relatively common. I have a round 7016-8001 as well but cant advise on all the color combinations. I think the two round models were 7016-7000 and 7016-8001 but stand to be corrected. I seem to recall however that there is also a very rare 7016-8000 model too that was actually marked as a Time Sonar watch which more commonly used the 7015 movements.
StartSomething said: