PRR ran its last E7 interchangeably with E8s in pairs taking over from GG1s at South Amboy.
I don’t think PRR ran them much in freight – by the time of the TrucTrain experiments they had plenty of superior E8s… and if those had a problem with back transition and heavy consists I suspect the E7 eould be no better…
Yup, that’s why GN’s E-7s soon ended up working (generally by themselves) on trains like the Gopher/Badger or other 5-6 car flatland “pocket streamliners”. They were bought to use on the Empire Builder, but couldn’t handle the mountains. Also why NP never bought E-units.