Re: pre PS1 box cars
Information taken from the F&C instruction sheet for " PS-0 40' 1938 Pullman Welded Boxcar" sic.
1938 "200 cars were constructed, 100 cars going to the Bessemer & Lake Erie with 6even panel Superior doors, 50 to the Chicago Great Western 6 uneven panel Superior doors and 50 to the Union Pacific as follows:The first 25 featured regular dreadnought ends, Murphy Panel roof and Creco doors, the balance matched the CGW cars"........ A second group of 500 was constructed in 1940. These improved cars featured an end with one additional "dart", and seven panel doors. The major change was th underframe, with three longitudinal members between the side sill and center sill - essentially a PS - 1 underframe."............." (200) Nickel Plate Road. (200) Wheeling and Lake Erie and 100 Pere Marquette.
Hope this helps.