I decide to closer examine the listing for the traditional GRAND TRUNK WESTERN auto racks. They have a clear numbering error the cars are numbered in 5 digits. This GTW auto rack flat car series is 6 digits 504000-504099. Here is a photo of the real freight car GTW 504054.
The greatly increased price of these flat cars with auto racks means that every printed detail has to be right.
The price for the tiny O gauge auto racks on flat cars is getting close to the price of the huge O Scale auto racks on flat cars.
Grand Trunk Western is my local railroad. There are photos showing the correct numbers and graphics.
Andrew