It was more a change in design that allows not only for easier construction, but much better access for maintenance. The old style units had a girder-type frame just inside the car body - the EMD BL-1 & 2 sheet metal shows this clearly from the outside. The later GPs had much stronger lower frames and center sills, eliminating the need for the girder and the wide car body. Although FP45s have full width bodies, the framing is the same as a normal SD.
The Illinois Railway Museum has a number of E & F units, including the BN Executive E-units. They also have a Santa-Fe FP45.
The answer to your first question about the demise of the F and Alco units, etc. can best be answered within several books, one in particular comes to mind: Mike Schaefer’s “The American Passenger Train.” In chapter 6 he talks about the streamliner era and the eventual “bottom falling out.” Good reading …
I cannot answer whether more steam loco’s are preserved than diesel/streamliners … however, my guess is that would be true. The steam driven loco holds so much in terms of majesty and history in American and Canadian railroading.
The only operating railroad left in North America that runs equipment from the old streamline era is VIA Rail of Canada. They operate regularly scheduled trains throughout the country. The “Canadian” (Toronto-Vancouver) and the “Ocean” (Montreal-Halifax) are just two. (I should add that new “Euro” cars - called “Renaissance” have replaced all but one train each way on the Montreal-Halifax route. Check www.viarail.ca for more info.)
Most of the equipment, aside from the locomotives, was manufactured by the Budd Company of Philadelphia, who also had factories in Canada. The majority of the cars running today were part of Canadian Pacific’s fleet and their transcontinental train, “The Canadian” (ViA Rail dropped the “The”). So, with a bit of research, one could actually determine whether the cars were “born”
In talking about streamliners, are you referring to the cars or the locomotives?
Fot the E’s F’s etc, it’s easy: Amtrak and the commuter agencies cut the number of buyers for passenger units. Freight units don’t care about streamlining as much. What we got was the EMD F40, then the F69, then they left the market. Amtrak gave GE a golden opportunity.
For cars, you have to look at the development of gallery and superliner cars. In theory, put on more people per car/train per length. My BN Racetrak tapes show the Burlingon running 2-3 car galleries with 1 combine baggage/smoker. Now they tend to run6-8 car blocks of gallery cars.
The superliner is a fine railcar. Put the passenger higher above the rail. From a coach seat, you may be able to see over the freight on the other track. Make better use of the lower section for the disabled & other special needs passengers. Hope you don’t mind going downstairs to find the bathrooms!
Lounge cars substitute for dome cars. The only view missing is looking ahead.
Western trains got them first, then as clerances were improved, easterners got a chance to ride one. It’s time for Amtrak to order a 3rd set of Superliners!
THe older Heritage fleet could no longer meet current standards. No more dumping the toilet overboard. A few were salvaged, others sent to Canada.