Hi, i just bought an mf-4 with mf-17, my mf-17 has the serial-no 17090. The special things are the clock and the date-thing...
The case of the clock was made out of two parts and the date-thing has 5 rings to set the date, you can adjust the year and the decade seperatly, the 5th ring in in the chrome barrel at the side.
Hopefully you can tell me the last serial-no, in very interested how many of these data backs where made or still exist.
Greetings from germany...