Looks a bit older than my Gitane tandem (1983). Hard to tell from your picture, but proprietary bits on mine include an 11mm rear hub axle in a metric-thread Atom drum brake hub, a dual-cable MAFAC brake lever to operate the cantilever brakes, and a single cable lever for the drum brake. Metric threads on both bottom brackets and steer tube. 40-hole rims front and rear. Otherwise fairly typical.