Here's what I'm adding to mine...
The CSX Safety Train tank was catalogued with the train. Black tank is not intended for this train, but I will use it as a stand-in...may remove some lettering. Catalogued at the same time.
For the flatcar (Dome Car 1), I purchased an Atlas O TTX flat with short bulkheads. The bulkheads remove easily. This flat is close enough for me. I have a few tank dome parts and several other items that look dome-like that can be painted. I'll add some railings to the flat and a door to the container. A little repainting and I'm good to go.
The real thing...
Atlas O flat...recently purchased from Public Delivery Track...
Here is a shot of the black tank commonly run with the train...