A reference for freight operations 1950 - 1960 and stock car operations in particular.
http://www.atsfrr.com/resource...r/Clinics/Stk/01.htm
the percentage make-up of the car fleet of the PRR in 1950 in comparison to the table in the attached reference is:
Boxcars 73
Hopper cars 92
gondolas 43
flat cars 4
stock cars 2 +.