Bottom one looks to be the latest with no numbers on the back. Do you happen to know the reference number or first few digits of the serial number?
Yup, numbers are on inside of case back, and last 3 digits corresponds with the lug number. Had to check for the serial, it's 8 231 XXX. Hope this is useful
Thank you. My latest one has a similar back and crown though yours appears to have central seconds. The serial number of mine is 8'242'xxx.
Early eighties I think... I had no horological input for the thread, so sorry it was the best I could do.