For those who want to define "phases" of GE locomotive designs...
The "classic" domestic U-series (late U28 to the 1977 model change) had a short vertical column of 4 ventilation slits on the left side of the low short hood. (High-nose units seem to have had the vents on the right side instead.) When the Dash-7 line was introduced, one of the spotting marks noted in one railfan publication ("Extra 2200 South," I think) was that there was a longer column of vents: 12 slits. Looking at photos in Marre & Withers "Contemporary Diesel Spotter's Guide," however, it appears that on LATE Dash-7 units there were NO vents on the left side of the short hood. (The units shown with this variant, except for an SP unit built with lights on the short hood, also lack the headlight box on the nose-- given GE tradition, however, it seems unlikely that the two design modifications were actually introduced at the same time!) Did these late Dash-7 units have some other arrangement for ventilating the nose compartment?
(And, just to prove that you can't assume a locomotive in service looks like one fresh from Erie, one photo in the book shows a Santa Fe B23-7 rebuilt with a U-boat-style short hood, with the short column of vents.)
The "classic" domestic U-series (late U28 to the 1977 model change) had a short vertical column of 4 ventilation slits on the left side of the low short hood. (High-nose units seem to have had the vents on the right side instead.) When the Dash-7 line was introduced, one of the spotting marks noted in one railfan publication ("Extra 2200 South," I think) was that there was a longer column of vents: 12 slits. Looking at photos in Marre & Withers "Contemporary Diesel Spotter's Guide," however, it appears that on LATE Dash-7 units there were NO vents on the left side of the short hood. (The units shown with this variant, except for an SP unit built with lights on the short hood, also lack the headlight box on the nose-- given GE tradition, however, it seems unlikely that the two design modifications were actually introduced at the same time!) Did these late Dash-7 units have some other arrangement for ventilating the nose compartment?
(And, just to prove that you can't assume a locomotive in service looks like one fresh from Erie, one photo in the book shows a Santa Fe B23-7 rebuilt with a U-boat-style short hood, with the short column of vents.)