I found this note posted by Robert Burns back in 2007:
"1954
was the year SR "officially" changed the color of hoppers, flats,
gondolas, etc. from black to "freight car brown/red", but it took
several years to get everything painted, so black cars ran up into the 60's.
1959
was the year the lettering changed from Roman to the Gothic/Block, but again,
it didn’t happen overnight."
