The GG-1 was a class of electric locomotives built for the Pennsylvania Railroad (PRR) for use in the northeastern United States. 139 GG-1s were constructed by General Electric and PRR's Altoona Works from 1934 to 1943, although mine is used by Brick Railway Systems on the New York - Chicago route. The real GG-1"s never traveled that far west in service, due to the overhead wires ending at Harrisburg, Pennsylvania.
The loco features Anthony Sava's sliding middle axle design. This means the middle axle out of the three on the bogie closest to the middle of the loco slide laterally back and forth to allow the engine over switches and curves that would be normally to tight to maneuver. These special bogies are used twice of course: one for each half of the loco.
The two outer wheels closest to each end are connected to the inner bogies via cup-and-ball parts. This allows them to swing freely and not bind up while still representing the right amount of wheels for a GG-1 loco.
The engine features moving panto-graphs for picking up (imaginary) electricity from the overhead wires. They are both in the raised position here, though normally the rear one would be used. The exception to this was if the rear panto-graph was knocked off or damaged by overhanging debris, which the engine would then have it's lead panto-graph raised in order to limp the the repair shop.
The model is painted in this fictional blue and red color scheme. This means the engine will be pulling some stretched 1980's style passenger car painted like the ones in sets 7715 / 7718.