Mike: Thank you. I'll save my money for more modern cars. Currently all of my ATSF boxcars are bright red 50 ft cars of one type or another, and I do need some older, or at least plainer, ones...
Kisatchie: It's your railroad, you can run what you like. Maybe in your alternate universe the ATSF wasn't as eager to repaint? I know the GN had boxcars in late 40s paint schemes at the time of the BN merger (1970), so it isn't impossible that some of the ATSF cars would have been around.
Dee: Have you tried making a cage from aluminum window screen? Most American termites don't chew through metal, and it can be cut with an old pair of scissors. Some aluminum angle from the hardware store will seal the seams at the corner, and it can be cut with Kiz's razor saw. Glue it all together with cheap epoxy, make sure the top fits tight, and they shouldn't get out.