The EA/EB, E1, and E2 models were powered by twin 900 hp Winton 201A V-12 engines in each power unit. They were standardized mechanically and in overall design. Union Pacific's E2 cab unit was distinguished from the slant-nosed EA and E1 units by its bulbous nose, round porthole style windows, and stainless steel ornamentation on the pilot and nose. The "E" designation originated to denote the locomotive units' Eighteen hundred horsepower, as opposed to the Twelve hundred horsepower "T" units but was later used to refer to all carbody constructed twin-engine mainline passenger locomotives units produced by EMC. Their twin V-12 diesel engine layout, Blomberg A-1-A trucks, and wheelbase would become the standard for all future E models. EMC/EMD has built all of its major components since 1939.