By 1910, Northern Pacific Railway still had on their roster a handful of flatcars 28-36' long from the 19th century. I worked with a few railroad historians, a historic-railcar wood kit maker, and several historic-railroad brass & plastic parts makers to create models of these cars.
The consist uses link & pin couplers; trucks with Lionel couplers are used for the loco and caboose.
I never found just the right custom decals to add roadname & numbering; maybe I'll restart that search soon.