I am not aware of any drawings that the C&TS keeps on file, but a good place to start would be to get a copy of Robert Sloan's book and check out the dimensions of the 6500 series flatcar used to make the C&TS passenger cars. The book is called "A Century plus Ten of Freight cars on the D&RGW"
Perhaps others here with connections to the C&TS info could shed more light on getting drawings of the coach bodies added to the flatcars. Photos, some time and a tape measure may be the answer.
I'm not sure what scale you are working in, but this could also be made as a laser kit to add to an existing 6500 flatcar kit.
What flatcar kits are available in Fn3, On3 and Hon3? I know PBL makes an Sn3 6500 series flatcar.
Jake Johnson