If anyone wants a key to the different PRR Track Scale abbreviations, a list
from 1923 can be found at
http://prr.railfan.net/lists/track_scales_1923.html. I have one from 1945
but it is not online. It is interesting to note that renumbering may have
occurred as the 1923 list, lists P-450 as the Indiana Harbor, Ind., Car
Shop, and not Fort Wayne car Shop (P-441) as mentioned by Mr. Thompson, the
others match what he said.

Brian J Carlson P.E.
Cheektowaga NY