Eric, my go to info is reading what HO modelers post. From what I’ve read. The Atlas HO caboose is fairly accurate minus a few details so I’m assuming the O scale one falls along the same lines.
As Gary stated. The 2 steel cabooses were built in 1959. The Rutland was done in 61. The only thing you could run with them and be protypical is the RS1. The green and yellow scheme did exist minus the Route of the Whippet on a few woodsided ones.