Manburg, noobs in GMT.
What's the difference between GMT and GMT II ?
CK, there were actually a few differences. Let me just take you to some of them.
The first GMT-Master that was re-named as GMT-Master II is the model ref. 16760 (which was also known as Fat Lady/Sophia Loren) issued from 1983 to 1988. The movement used was 3085 that has hacking and quickset functions. It has also now been equipped with a sapphire crystal, though the markers are still using tritium as used in the 16750 and 1675. The crown protectors are also a bit bigger than its predecessor.
The most marked change is however the GMT hand is now no longer being controlled by the hour hand. Meaning, it could be adjusted independently without having to adjust the hour hand, which is the case in GMT-Master (even the ref. 16700, as mine). Thus, with a rotatable bezel, the GMT-Master II could now display three different time zones simultaneously, as opposed to two in the GMT-Master.
Hope that helps a bit.