Speaking of their boxcars, there was another series that they offered in a kit form.
1. There were the el cheapo, molded-door cars that matched the Lionel 34xx series.
2. The molded-door cars that almost exactly matched the 6464 series in size:
click 3. The larger, almost scale cars with sliding doors:
click The 6464 size were in a kit form. The parts were the shell, floor, two trucks with non-operating couplers, two self-tapping screws to fasten the trucks, and sometimes a brakeman who could be glued inside the open door. The other side had a closed door.
I have a couple of the PRR versions and a few undecorated, white plastic, ones in original boxes.
There are also tank cars, gondolas, hoppers, flatcars, stock cars, and cabeese in undecorated kits. I have a few examples of each that I bought from a toy store that was closing a number of years ago.