I checked photos, they are virtually identical... one pair of vertical ribs is wider...
The main difference is the doors, the original 800 NSC cars which is what this car are base on had 10’ wide doors, the rest of the 2900 FBOX cars have 12’ doors
And were manufacture by Gunderson, Trinity , Johnston and NSC.
It no big deal and i am getting a few since they are nice cars and have a different pain scheme than from before.