Gitane Mexico no. 1903? I'm seeing Bocama Professional lugs and swaged over seat stay tops and the same contours of chainstay crimping on my old TdF. It has what looks to my eyes like a Stronglight P3 headset and a Stronglight 93 chainset. If you have a 26.4 mm seat post, that would indicate metric gauge 531, and that model had a tretubi frame.
If that is indeed it, it dates from the era when Gitane swaged over the tops of the seat stays instead of doing the willow-leaf tops, so that's what, 1971-75? @
verktyg will be hopefully be along to lend his Gitane-discerning eye ...