Hi Ed:
I have been engaged in a similar exercise for tank cars which may have run on the BCR during the 1970s. Of course, prototype photographs and switch lists will provide clues as to which tank cars were seen.
For these particular examples, you will need to know their service dates. Your best reference for this is the Official Railway Equipment Registers which were published each year. These can usually be accessed at libraries.
The first two cars carry SHPX reporting marks and belonged to ACF Leasing (Shippers Car Line Division). Tank cars were usually built by specific companies such as ACF or Procor and then leased to various chemical companies. Assuming that the model manufacturer has used actual reporting marks, you can look up SHPX 3509 and SHPX 766 in the ORERs for the 1970s and see if they were in service or not. Same with BMX 810.
The ORERs have provided me with built and out of service dates for all of the PGE/BCR freight cars as I was able to obtain copies of the PGE/BCR section for most years. Private owner cars such as your tank cars are a little trickier because you have to find the actual books.
Tim
