I have been reading about Alexander III (The Great) tetradrachms, and ran across some interesting information on dating these coins, specifically concerning the depiction of Zeus, a likeness after the Temple of Zeus in Olympia. In several sources I read that early or 'lifetime' issues are usually struck on
thick, chunky flans and show the legs of Zeus parallel to each other. Many authors seem to concur on roughly dating these by Zeus' leg position, although they note exceptions too. There is confusing and contrary research, but I would not be surprised if a stylistic progression from straight to crossed legs happened slowly across various mints, versus an immediate change everywhere.

That said, I see many coins sold as "lifetime" Alexander the Great tetradrachms (356-323 BC) showing crossed legs like the coin below:

This coin also bears the lambda/torch mint mark for Amphipolis,
another marker of posthumous issues. As with most of the torch-lamda tetradrachms, the above specimen has Zeus' legs resting on a stool.
Then, I ran across this Alexander III tet, showing parallel legs on Zeus and some other interesting markings:

In a paper titled
"The Dating of the Coinage of Alexander the Great", I found a reference to the symbol at the left of Zeus:
"Group II B, beginning around 342/1... distinguished by the common reverse marks of a prow, stern, janiform head and sometimes a rudder was struck until c. 329/8. Thus, the chronology of the Philip series places Group II B during the time period of the death of Philip and the rise of Alexander."I'm surprised that I actually found the same janiform head, and how it suggests a reasonably early tetradrachm for Alexander the Great! Unfortunately, this coin is out of my budget, but learning something new can be as much fun as buying a new coin.

(source material used here is linked above)