The 24 's when you see them in pics on mostly on truck doors and the 30's are mostly on the bank of small tanker trucks . I am assuming that is the reason they were all that I have seen single sided . But now we are finding out there are some double sided . RARE
Went and visited a collection today and asked about the owners 24" sign that he has. His is also double sided but again it's the McColl Frontenac sign. I'm thinking the McColl sign is the only version that came in 24 inch as I have now seen at least a half dozen examples and none of them advertise motor oils or gasoline, only products. I'd like to find one that is for sale.