I was going to put this in Mikes #75 thread alongside Derrell's thoughts on mounting positions.....
This photo essay illustrates the complexity of the need to identify not only the Locomotive characteristics but also to define a particular era in service. Lamp styles and shapes are also presented here along with the stack changes if possible to define the era. One can also note that the Handrail was used often but not every time to act as a conduit for the wiring once the Lamps had been electrified, the wires exiting usually through an angle-Tee but sometimes a standard Tee pipe fitting.