But the second part of your answer is not right.
Let's take the example of the Pam 192, which was the Chrono Tantalium.
Panerai didn't release the 300 pieces in the same year, but till 2006, if I remember correctly the situation.
Though, the Pam 192 always had the G letter, corresponding to 2004.
Same for Pam 203, which was " H "=2005.
Idem for a no Limited Edition.
Best,
Nicolas