To my knowledge Grand Jubile's never came with triples. I've got a 1976 GJ and it has a Stronglight double. Still a great bike, but I don't think a triple was ever an option on them.
EDIT: Your Moto is most likely an early 80's. - Catalogue image exists for '79 and it looks very similar to yours, but colors were only black or gold in '79.
'79 model specifications and photos here:
http://equusbicycle.com/bike/motobecane/1979/index.html