I have been asked for some info on the X31A cars, so here are some facts:
From the mid-thirties production years, there were around 7300 in service, more than many roads’ entire fleets;
In 1943, there were 7285 X31A;
In 1949, 7250 cars, now the second-most common box cars on the PRR;
In 1955, 7195 remain, while X29 numbers are falling;
It is not until the 1960’s that X31A numbers fall, and even so, there are 6404 SD and 578 DD cars still in service in 1964.
The X31A DD were widely used in AUTOMOBILE service initially;
Many other X31A are used in dedicated service, including: auto loading, auto parts, linoleum, and even a group of coal tar pitch cars;
There were even X31A in dedicated coil steel service, some of the first such cars used this way;
There was even a group of dedicated silk, later rayon, rack cars.
And of course, the thousands more in general service.
With the number of photos I have looked at, the X31A went virtually EVERYWHERE.
Now you know.