Tim's formula looks really good. Or if you prefer an acrylic paint, try Modelflex Light Tuscan Oxide Red 3:1 with Modelflex Rust, then mix in a couple drops of white until you can just see it start to lighten. This gets you a color that's close the fresh NP mineral red. For a well-aged stock car, add maybe 20 percent maroon tuscan oxide red and then a drop or two more white. Airbrush unthinned at 12-15 ppi to keep it satin smooth.

BTW, builders photos first supplied to me by Matt Herson show that the interior of these cars was unpainted wood. There were small interior stencils over the doors with the car number and some other information. Now there's some rarely trodden ground in freight car modeling.

Chris Frissell
Polson, MT