a couple comments
1) The issue of quality over quantity OVER SIMPLIFIED w.r.t tanks. The German Panzer was superior to the Sherman but better relibility, easier to fix in the field (garage machanic), and numbers were large factors in the NAZI defeat.
We could afford to loose one Sherman (due to numbers) whereas the Germans could not (again numbers).
2) it always seems that a new airframe design needs to be developed from scratch. This philosophy also holds for spacecraft. Why can the airframe outline design for the Space Shuttle not be used for the next generation Space Shuttle (now dead). The shuttle needed many upgrades but we knew the airframe shape and where bugs might be to be fixed.
For a railroad connection, the PRR GG1s had worn out frames but the body was a classic. A new electric design based on the GG1 body with New frames (maybe diesel trucks), up to date (late 1970's), electronics, and MU abilities would have been simple. In 1982 there was a study (I recently saw a copy) of electrifying West to Pittsburg. The proposal was a dual use engine like the New Haven FL9s that could be either electric or diesel. It was to have been based on the SD40-2 using a longer hood and extra electronics).
3) Interestingly, With the argument on the Space Shuttle and the US Military being consistently stripped for the "Peace Dividend" (like Truman's administration did after WWII and before Korea), out space program is in the hands of lowest bidder and the military will now need to fight major wars with mercenaries.
FWIW
Doug vV