15mm - Fn3 - 1:20.3 D&RGW 6300 Series Flat Car
The 6300 series flat cars of the D&RGW were original built as a 40' longwood flat cars, Class 22 30 ton cars #6300-6314 in 1926.
In 1934 (Not 1937 as indicated by Sloan.) these cars were re-enforced by adding rails to the underside of the side sills and adding 7-3/4" queen posts to replace the original 3" posts to add extra strength.
Stan Schwedler indicates that #6313 had the rails added to the top-side of the car.