A large number of PRR steam locomotive models have been imported in O scale over the last 45 years, but unfortunately at times some have been equipped with marker or classification lights that are incompatible with other era dependent features such as post 1940 wide spaced PENNSYLVANIA lettering or post WWII drop pilots and trainphone antennas.
An authoritative article on PRR marker and classification light practices from 1922-1957 by Elmer Steurernagel was published in PRRT&HS’s The Keystone Vol 35, Number 1, Sping 2002. I've found the information helpful in harmonizing PRR locomotive details with the era I'm modelling.. For those that do not have that that issue of The Keystone below is an overview of the changing standards.
· 1922 - PRR adopts a cast 2 piece (claw foot/rotating 4 lens helmet head) fixture for class and marker lights on steam locomotives
· 2 pair of marker light fixtures - 1 red lens, 3 amber lens
- 1 pair mounted on the pilot beam
- 1 pair on the tender deck corners
- 1 pair of classification light fixtures mounted on the smokebox - 2 green lenses, 2 white lenses
· 1929 – shops ordered to remove classification lights from locomotives assigned to yard and freight service (except M1/M1a's and other freight locomotives regularly assigned to passenger service
· 1935 - shops ordered to replace inside and rear facing amber marker light lenses on engines and tenter with blank discs - leaving 1 red and 1 outside facing amber lens
· Dec. 1939 - shops ordered to relocate tender marker lights on K4s and I1s Kiesel tenders to rear shelf platforms - effected classes include 110P75, 110P75a, 130P75, 130F82a
· June 1940 - PRR ceases to use the train classification rule (extra, second section following) - shops ordered to remove classification light fixtures from locomotive smokeboxes
· June 1942 - PRR adopts smaller oblong (tombstone) marker light fixture for application to smokeboxes in lieu of pilot beam mounted marker lights. In their housing are two lenses yellow above, red below, Not all locomotives were re-equipped with the new markers
· Aug 1946 - PRR adopts a a smaller single red lens round "bulls eye" marker light fixture for use on smokeboxes. This is the most common marker light fixture seen on postwar PRR steam locomotives – however many with tombstone markers retained them until dropped from the roster
