You can reskin with these programs: Gimp(free), DxtBMP(free), and RWTools(donation of about 10 bucks required). These are all affordable by you if you are willing to pay 30 dollars for a route/reskin. It really isn't that hard, look for tutorials on youtube, thats how I learned to at-least do basic texture modifying.
-Harrison CSX railfans are how tomorrow moves! Future owner of HSM Co Transportation- Rolling into the future. "If I could return to those boyhood days of mine, and that green light on the Southern, Southern railroad line."
I'm not sure what era of the F40 they're modeling, but I know for fact that they didn't come with ditch lights and probably weren't added till the early nineties, shortly before they were replaced by the Genesis series.