What'd I do? Figured out what's what with K-Line aluminum passenger cars. The PER just acquired a retired business car in PRR livery and management wanted the trucks switched out. It turns out these cars are the same design as Lionel PW extruded aluminum cars so its pretty simple to take one apart.
You just remove the 2 screws that attach each vestibule to the floor, remove the vestibules and slide the floor endways until it is separated from the extruded car shell:
The car interior is attached to the floor by tiny screws from underneath.
The underside details must be removed (one screw at the left end in this pic) to access two of the interior retaining screws:
Here is the bare floor re-inserted to show the design. The ceiling indirect lighting can be seen as well as the wire that plugs into the floor wiring.
And there you have it:
Ready for dinner service.