The ILW gp7ds are remanufactured, as you would expect, from EMD GP7s and similarly framed geeps. They have an all-new AC drivetrain – powered by a Cummins QSK50 – for approximately 2100 HP & 82000 pounds of starting TE.

The first one was a rebuild of the Bangor & Aroostook’s ex-bicentennial unit. This engine was being kept on the roster for historical reasons, so the locomotive went to ILW with instructions to disturb the carbody as little as possible. A QSK50 is not even close to a tight fit, that part of the remanufacturing was easy; plumbing the EMD radiator, on the other hand, was enough of a pain that ILW stopped even trying to save that section of the carbody on future rebuilds.

Subsequently gp7ds all came out of the shop looking less like their donor locomotives; the radiator & electrical compartments were replaced & the roof was cleared of fans, so they all looked more the same than like their donor locomotives.

However, as time went on the remanufactured units went back to using more of their original carbodies; later versions – like Ottawa Valley’s ex-GP20 #1587 – kept their electrical compartments (not the internals; those were still replaced with AC components) and most of exiting roof hardware.

The `d' suffix is, as you might guess, for doppelgänger.