How did this go from a question about SD-80ACE's, to SD-70 ACE's? HUGE differences between the AC/DC locos, and the technology on those ACE's certainly costs more money. Headlite locations and positions, and horn placement, etc., are mere cosmetic variations, dictated by the purchasing carrier, and would certainly not be any way of accurately identifying a loco. Try looking on the side of the loco, as most larger carriers identify the model number, somewhere externally. A "lightning-bolt" on the loco, near the number on the cab, is also a good indication of an AC motor. The AC's are preferred power for engineers, as they will accept more "abuse" without damage. (imagine holding the train on a grade, with the throttle, instead of the air......) I myself would not care if I ever saw another Dash-9, or any of the other locos with the so called "wide-cab" (Why the hell do people call them wide cabs? the cab is the same width as older equipment. Perhaps they mean wide nose.......) An SD-40, 50 or 60 is fine with me, and I wouldn't care if I never operated a GE product again, excepting some of their very tiny switchers. Just my opine, though, yours may differ dramatically...............