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
Modified my response to "as built". Yes railroad shops over time changed things. There would have been variations in the fleets as units cycled through. The resources above give information on as delivered.
Steve