Connecticut may have been the first ... in the early 1950's, James Melton, the opera singer, had them on dozens of restored antique cars.
Description found with this photo says: The New York Central had several auto-carrier Flexi-Vans in the early 1960s. This is a publicity shot of carriers with new Chryslers on their way to New York City in 1960. New York Central photo Isn't that a train load of Valiants?