You wrote:
"Another thrift shop mystery. I recently picked up a 70's era Gitane for $25 at Purple Heart. I'd like to know more about it. It's a well-worn forest green with chromed crown and fork ends. It's lugged and appears quite light. The decals are silver and barely readable. I can make out the words "Interclub" and "Service" on the downtube. Also on the downtube decal, it says "Champion" and I believe "Course." I can also make out the word "Course" on the the top tube."
I believe that this was the "amateur racing bike" and it is likely to originally have had sew-ups on Normandy hubs, Simplex derailleurs, etc. If it does not have an integral derailleur hanger, it was not a high-end Gitane, if memory serves. If it was, was likely a Simplex and the tang was sawed off to hang a "real" derailleur. (Shame, that, since I've routinely tapped and ground them so they work fine with campy-type derailleurs).
I would also suspect seamed tubing.
If my guesses are right, you got your money's worth. In parts.
harvey sachs
cold in Northern Va