All vintage (1930's-1950's) Panerai cases apart from the last one (2/56 aka Big Egiziano) were made by (or on behalf of) Rolex. And indeed the Rolex/Cortebert Cal. 618 was used in all these case variations.
So one may argue that Panerai is in fact...
...well that's not true, but if you want to open up that debate, you must visit the Panerai forum. Sorry.
Asi
Are you a book of historic fairy tales???
As Asi mentioned in the thread, all vintage Panerais were made by Rolex.
Thanks for sharing your knowledge.