From Interurban Special #37, page 791:

The final group of second-hand cabooses was purchased from the Richmond, Fredericksburg & Potomac in 1950. This official PE view, taken at 8th Street Yard, shows 1984’s first style of PE lettering which was later changed to resemble SP’s block style lettering of the late 1950’s and early 1960’s.

Edward Langer Collection