PPG should be able to help you (however, your local PPG jobber might not want to pursue this).
Try calling one of the phone numbers below and give them PPG-10419 (originally Ditzler, DQE-10419) as the code and tell them the year/color you are looking for (1952, Mariner Blue). Mariner Blue changed in 1953 (different shade and different code - same name).
440-572-6100 PPG Color Library - had all codes
440-572-6111 PPG Tech Services Refinish (gave me the number for the Color Library)
440-572-6871 FAX number for the PPG Color Library
The above numbers are 6-7 years old. If you try any of the numbers, would you please post if they are still good?