Why not start with photos of trains/yards taken in your era(s)
and in your area(s) - and if possible even taken on your RR? With
just the date and the reporting marks (RR, not number) you should
be able to then go to the appropriate ORER(s) and get car number
ranges and other useful data. And probably also fill in some
'likely alternatives' you didn't find a picture of ...
Don't necessarily limit your self too much - a pic of a tank car
in Chicago is likely to 'work' for a layout based upon say Dayton
or Minneapolis ...
Perhaps you will need to go back and recheck the photos after
you have studied the ORER(s).
Wheel reports would be nice - if you have them ...
Armed with the above - you should be able to make reasonable
choices and/or ask better questions (which result in better/more
- Research can be both addictive and fun ... Jim
P.S. Finding appropriate cars for pre-WWII freight cars - even
just box cars - can be an exercise in frustration control.
Some times it is even difficult to find an "adequate stand
in" for anything before 1935. Or decals.