The 1921 "All About Tank Cars" from Standard Tank Car Co. shows an ARA
stencilling diagram for an ARA Class III car with an "Inflammable Placard"
on the side. If it were a Class V car about 20 years later this would answer
the question, but it is probably nothing more than a start in research.
Subject: [STMFC] Placards for Liquefied Petroleum Gas
Which placard is correct for LPG or Propane in the late 1940s, "Compressed
Gas" or "Inflammable" (or another one that I can't even read)? I have the
Microscale decal set #87-975 with the "transition era freight car placards".