As the catalog shows (thats an 1988 version as I recall), 531C was used on the Vainqueur. All I’ve seen of that model were red, however, the internal cable routing from top of tube on your frame is I believe consistent with that model. Gitane reintroduced the Team Pro/Replica in 87, it was made w/ 531P and cables were routed up from bottom of tube. The first year of Systeme U they initially used these blue frames. The Exploit in this catalog was the Team Pro/Replica from 1987 with new paint job. Yours could be a repaint/redecal. If so, it could also the Success model and actually be 501. Here are my 87 Team Pro/Replicas, one owned since new: