My understanding is that the "Standard" three pin Stronglight cottered crankset is Model 54, and the more expensive "Competition" three pin Stronglight cottered crankset is Model 55. Here are some later datapoints to add to Mark Fulton's earlier datapoint for the Stronglight "Competition" model 55 three pin crankset:
1950: Mark Fulton's 1950 Locomotief T de F 1955-1969: Holdsworth Aids to Happy Cycling catalogues
Peter ...................................... Peter Brueggeman La Jolla California USA pbrueggeman(AT)ucsd.edu
I just aquired a Stronglight model 54 crankset(steel, cottered, competition stamped, 3 arms) in very nice condition. ... Does anyone have any idea on when these were made ... thanks Barry scott Brooklyn, NY