James,
The D&RG Class 56 and Class 60 (aka C-16) had slightly different driver spacing as evidenced by D&RG Folio Sheets. It was a matter of inches here or there, but they were different.
The frames on the B-4-(A,B,C,D,E,F) C&S locomotives were the same throughout the B-4 Class as I said before, but were probably ordered to spec. by UP as the locomotives were built by Baldwin, Cooke and Rhode Island and were from the CC, U&N and DSP&P when the C&S was formed.
Each Railroad had its own classification system, true, but each followed a logical sequence.
Rick