This has to be one of the easiest kitbashes ever. Definately not cheap though as it involves a KATO SD40.(either scale-this one is N scale) and an ATLAS GP38 long hood.
Did you actually use two complete locos? I think both Atlas and Kato sell undecorated shells for all of their recent offerings at least. Of course if you did use two complete locos, you could always use the sd40 long hood on the gp38 chassis!