Greg_H,
The PPG code given by BiggerHammer is the correct code and a formula for most PPG auto paints should be available. I found my local PPG shop to not be interested in finding a formula, so I called PPG's paint library and they were quite helpful. They had formulae for all my 1954 colors (except white and black for trim), including Mariner Blue, Pulsay Gray, Maroon (Suburban interior side panel trim and seat frames), Anvil Gray, and Thistle Gray (bumpers and inner grill bars).
The PPG phone number has changed (its been 5 years since I bought paint from them) but you might be able to find a phone number by calling various numbers in PPG (check out the website link given by BiggerHammer).
It is impossible to be sure what the colors truly were. 50 year old paint chips and aging/oxidated paint (even in protected spots) are most likely not "true" colors. On top of this, the PPG pigments have changed over the years. Nonetheless, PPG seems to be the best source for old paint colors.
Transport Blue could also be described by some people as Baby Blue or Powder Blue. My Dupont/Ditzler/Acme 1954 paint chips for Transport Blue do not seem to have any green tint.
Good luck,
Tim
