I went to the Old CGW Box Car Mecca. That's right, Boone, IA.
Thanks to the miracle of MOW service, there are three CGW box cars from different builds still in good condition.
The 'X-29' can be modeled with just a new door (if you can ignore rivet patterns) and the 1937 car needs 'dart' ends. Unfortunately the 1932 car isn't one that Atlas decided to make and would need new roof doors and ends.
Jason