First, a background on the Lionel 21" Budd Passenger Cars. The cars were originally in the New York Central Empire State Express set with a dome car that's been added. For all of the cars they have the skirting between the trucks which is wrong for the Amtrak versions - they were de-skirted prior to Amtrak The Baggage Lounge is correct for Amtrak, but was not used for an extended period and mostly on short haul trains. The Coach is also correct and saw general service mostly in the east. The Diner is also correct and is a very close cousin to a Seaboard Air Line Diner (different roof vents). The Sleeper is also correct, but was not used past 1976 or so. New York Central was unique in the 10-6 Budd Sleepers were built for vestibule to the rear operation vs. the other railroads opting for the vestibule to the head-end. The Dome is not correct and is an off shot of something I've not seen. The Observation is not correct for Amtrak, as the Penn Central sold the Empire State Express observations to Mexico before Amtrak.
I did an experiment of converting the Lionel trucks on a Pennsy Car (same trucks as the Amtrak ones) it they came out fine. I also used a Shapeways coupler pad to get the Kadee Coupler height precise.