Ulf,
Never say never, as they say. The car had a non-original wing installed, the trim around the deckled opening is not original and the car has definitely been re-painted at least once (as reported), so there are many possibilities (including that the deck came from another car at some point). Regardless of how nice the hole looks, it seems quite unlikely to be a factory hole because even the factory would have started with a solid deck lid and added the hole in the same way a competent fabricator would have. I tend to agree that it was likely an added antenna. Since there is already a front fender antennae, maybe it was for a CB radio which were very popular in the late 70's and early 80's.
Mark
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