I have used Shapeways to replace the bolsters on my Atlas Reefers. They may even work on Atlas box cars.
https://www.shapeways.com/prod...ght-car-body-bolster
They have gone up in price, I believe they were $4 the first time I purchased one, now they are up to $8 each. It looks like Atlas is conforming the theory of supply and demand.
I hate to see the under frames of the hoppers falling apart. hopefully Atlas will solve this problem. They made a dollar or two when they made the troop sleeper frames available.
Hope this helps.
Richard