Hi Barry,
I have a set of Stronglight cranks that came new on my 1950 Locomotief T de F. They're three-arm cottered, bolted to Simplex one- to-two adapters to Simplex rings. I don't know if they're model 54, all I can find on them are the "Stronglight Competition, Marque Deposee" ovals. But if mine are 54s, they were made in or before 1950.
Mark Fulton Kind of wishing I'd bought a houseboat instead of a mobile home in Redwood City California
PS: Don't worry, my bikes are above flood stage. So far anyway.