@L & N posted:Things like vents, portholes, fans, and doors tend to be more specific to the model (type) of locomotive. Items such as lights, horns, grilles were optioned by individual railroads. While specific to ATSF here are 2 sources to help you determine F7 from F9:
Steve
One still has to be careful as locomotives went through the shops. Take the 308L for instance:
On Santa Fe's books, it's still an F7, although externally it has received the vertical side vents, FARR stainless steel grills and 48" dynamic brake typical of F9's.
Rusty