My immediate thoughts also turned to Gitane, even before reading past the first post. But the rear end has me wondering about whether it is a Tour de France model or not.

My friend's TdF of early 70s vintage had Simplex dropouts with a RD hanger (for Simplex derailleurs, natch). If you wanted Campy or Shimano (or pretty much anything that wasn't Simplex) you could (a) tap the hanger or (b) saw the thing off and use the adapter plate as this one has. If this one had its hanger hacked off, I'd say it's a TdF and call it a day. But if it never had a hanger, might that mean it is a Gitane Interclub (the next model down the food chain, IIRC) rather than a TdF? Just askin'.