Would anyone be interested in the "Photography Game" here?

[Puddlejumper]

Ralph,
I never noticed, but I would bet that is what the big "S" means.
Now where is your PC picture? We have been waiting for you. Don't you have any?
Charlie

The "S" stood for service. As in company Service. PRR used it also, on covered and open hoppers and boxcars for transporting sand, ballast, etc. anything the company needed moved between terminals but within the confines of the system IE no interchange.

Dave