500-600? where did you get this quantity from?
Over the decades it seems that many knowledgeable parties are increasing the amount of Vintage Panerai/Rolex Watches.
Personally I will stick with what I learnt t a time when Panerai was not too famous from trusted parties (Panerai in Firenze, and Marina Militare staff) . This to say that quantity of PANERAI 3646 was said to be no more, maximum 160 pieces.
I would want to learn different, but till such a time…
Rolex 3646 California dial, not all 3646 were distributed to or by Panerai in Firenze.
Concerning Panerai in Firenze, all 3646 fitted with a Radiomir Dial were actually delivered by Rolex to Panerai in Firenze with a California dial, of those pieces all have a Rolex (engraved) case back (deliveries late 30’s to very early 40’s), those 3646 are housing a Rolex (engraved movement).
There were a few 3646 California dial delivered to the GPF boutique in Firenze, those I know/saw had the same configuration than those destined to the Marina Militare.
Passed 1943, I am not sure what happen and who is who…
It is alleged that Rolex directly (or indirectly) delivered some 3646 to the German army, I do not know much of those versions not did I learn the specifics.
The Cortébert Rolex 618 was used by some other manufacturers, (Elgin for example).
In the case of the watch here shown, no doubt the dial is repainted a repro! The case (based on the photos) seems strange, moreover the crown tube on the case is no correct. The movement can be correct with its engravings, if it is not related to Panerai in Firenze (so far of any watches I know related to Panerai in Firenze or Marina Militare, none I saw had this configuration), and none I saw of the Panerai in Firenze or Marina Militare 3646 had this case back configuration.