I bought a couple of Athearn cars that I'd like to change to metal couplers and trucks. I found Kadee's conversion chart for couplers, is there a visual reference chart for trucks as well? One is a 40' derrick flat car, which it looks to me like the Bettendorf truck fom the Walthers reference book. The other is a Walthers Dynamometer car. Kadee's website has fairly small photos that make it difficult to match type.