Steamwolf: I will post pictures of the consist as it appeared in the box. Likely be a day or so as I am working tomorrow. Happy to share with you. Here are some descriptors in the mean time.
S.C.C.X 652 Shell Tank Car Yellow tank, red lettering, black dome and ladders. This was the "extra" car that distinguished the
# 45225 set from the #45200. Both were available 1951-1952
GAEX # 1950 Green and Yellow Box Car, lithographed, sliding doors
# 44572 C&O High Side Gondola, Black with white lettering and "rivets", lithographed
#1951 Santa Fe Caboose (red with black roof)
These all had "High Semi - Scale" trucks with metal "pickle fork" couplers. The key to making this work with the #21 is to make sure any cars you get have these "high" trucks. They only lasted a few years in the 50's and they were put on the cars specifically to mate with the #21 loco. These same cars came with other Marx trucks / couplers but those are not fully compatible with the #21.
Good Hunting...these cars are not normally too rare nor too expensive and may be available on e-bay. I know what you mean about the Marx motors, almost without exception no matter the condition of the engine when I find them, the Marx engines run (spark, stutter, and otherwise make noise but run).
Thank you for the compliments on the set.
Regards Don
