The closest thing I've seen to Metroliner information for the modeler is in the information in a book I have published on Behalf of the Budd Corp. circa 1981 and in the surprisingly accurate Bachmann HO Metroliners of the early 70's. The original release of those were center drive, 8 wheel drive powered units with metal sprung Faively pantographs that look and operate like the prototype.
Having said that, I'm sure information is available from what remains of Budd or at the State Archives in Pennsylvania. The only intact Metroliner is at the PA state museum and it's a rare cafe car at that. It never got Amtrak paint and sits outside in its original PRR / PC red stripe surrounding the windows.
Joe Acri is probably the researcher to hire in PA if you want to obtain all the available documentation.