Just stepped into this thread.
Well, unfortunately, being both French and a Heuer enthusiast I have to admit I do not have a clue... at this stage.
Certainly due to the the fact I do not have any "Fab. Suisse" stamped dials in my collection.
Eric (aka Lechnereric) as many of of them as the efficient Heuer hunter he is, he maybe has some clues,
I'll drop Eric a message to figure out.
Stewart brought to us something which sounds like the beginning of an explanation with this auctioneer catalog extract.
I can also try to get in touch with some of my contacts and, if anything interesting pops up, I will forward the information.
Cheers,
Laurent