"While this prototype is available from SPH&TS/Intermountain, Bruce Petty uses the Tyco cars as an inexpensive stand-in for SP Class F-70-7:
http://www.lariverrailroads.com/flatcar.html
Tony Thompson replied: "But keep in mind that the very accurate Red Caboose flat car is a GOOD model of that SP car class. The RC dies are now owned by, and used for production by, the Southern Pacific Historical & Technical Society."
Very true, but Bruce makes a very valid financial point. Not all of us can afford to drop $1.2K on a train of models, no matter how nice they are. I can't fault his decision, and each one of us has to balance what we want and what we can afford.