Determining Car Era?

[Amalynn]

So I model specifically from 1937-1942, and have found myself with a lot of difficulty knowing what models, roadnames, and liveries are appropriate for interchange in the time that I model. I was wondering if any of you might have suggestions for keywords, recommended reading, suggestions of anything specific, or just general advice to help guide decisions on whether or not a car at a swap meet, on ebay, or just for sale at a retailer is appropriate to my time period or not.

[Charlie B]

The beginning year of you modeling won't apply here as there would be cars built after 1900 still in service with even older cars used in MOW service. Most of the cars would have friction bearings. Ending with 1942 would also give a little leeway due to WW2 and the lack of production of anything non-essential to the war effort. You sometimes can rely on the build date applied to the model also, and sometimes the only thong that makes a model too new would be the build date. 
DrWayne models in the thirties so I recommend you look at his pictures of the cars he has detailed and those will all fit right into your time frame. 
Another great source of information is the local news papers from that time frame, though most of the information about trains will be wrecks, and a real long shot would be a local library with a copy of the Car Builders encyclopedia for those years and the railroad equipment registry would also be a good resource if their was one ton be found. Digital copies are available here: https://www.nmra.org/library/kalmbach-li...-registers 
And you can always ask another modeler or the person selling at the shows. I generally fing folks selling at shows to be very honest and helpful, it's just in our nature.
Charlie

[tompm]

This a great resource. The only problem is the timeline begins in 1945. At least it will tell you when something is too new, aka did not exist before a certain date.

The Railroad History Timeline - A Tool for Modelers