dave: The Space-Dweller was a limited-run, Japanese market-only 1016 that was sold in the mid-1960s. Most of the writeups about it will tell a little story about how it commemorated the visit of Mercury astronauts to Japan. I don't know if this is true, or if it's one of those things that gets repeated over and over without ever being confirmed.
Anyway, it's identical to the Explorer of the time, except for the text on the dial. And that's why the gen sells for ~$40,000, rather than the $4,000 a lot of ordinary 1016s go for!