Originally Posted by prrhorseshoecurve:
The yellow cupola is. It signified east-west unit trains. A Gray cupola was for north- south unit trains.
Actually, in the 60's the yellow cupola signified a cabin car in pool service (could wander anywhere, not restricted to a certain region). Beginning in 1963, cabin cars in pool service in electrified territory east of Harrisburg had cupolas painted gray. Yellow cupolas became pool service in non-electrified territory. Note that the gray cupola cabins generally would not have trainphone antennas since the trainphone didn't work when overhead catenary was present.
For more information on steel cabin car paint and lettering, see:
http://pennsyrr.com/index.php/...r-painting-lettering