Does anyone know where I can get PRR position light signal disc heads plastic and brass?
Try Integrated Signal Systems, http://www.integratedsignalsystems.com ; They specialize in prototypical signals and accessories for virtually all prototypes, B&O, PRR, ATSF, NYC, etc. They also have the masts, signal towers, and dwarfs.
NJ International also has PRR signals.
–Randy
Oregon Rail Supply sells heads and complete signals.