PC: F-7's

[Norman O Mueller <nmueller4@xxxxxxxx>]

I lived in Philadelphia during the Penn Central era.  I remember maybe
once in all those years seeing a freight train powered by EMD F units. 
It was always electric power or diesel road switchers at the point.  Were
the F's kept on the western half of the system?  It seems the pictures I
have seen were taken west of Pittsburgh.