AHM / Roco had a heavy duty fishbelly flat in HO similar to the car in the picture. I don't know if the car has been offered in the recent decades but it did exist (along with the more familiar depressed center flat) as an AHM import during the mid 60's. AMTRAK had some of these cars which they inherited from DODX. Charlie Vlk
Charlie,
The Roco car is pretty good for the 1953 Magor built cars. USAX is not one of these (obviously, given the 1949 date <G>, but also due to some construction spotting features like sill height) so that's why I was asking. I am curious to know more about its history.