Here's a UP ES44 I've been working on using Erik's Pilots. This ES44 has been converted to full time 2 Rail, started life as a standard MTH "Hi-Rail" model. I've also done a SD80mac using the SD90 pilots. I still need to remove the shell and make new full length handrails that are mounted to body, same as I did for the handrails at the anti-climber. I also added a few of my own details such as grab irons and hoses. Color matched the parts using Scale Coat II UP Harbor Mist with a coat of Dull coat, all parts were painted with an Airbrush to keep it smooth.
Erik did a great job on these, I hope he does more in the future. I know this takes a long time to develop as we model in Revit for BIM ourselves. I'd guess between 30-40 hrs per pilot including all the needed measurements and studying online pics of the prototype. They are fragile, hopefully in the future shapeways adds a different print medium option. These would be awesome in some type of printed metal but I'm sure that would be $$$$$$.
Side note; does anyone know if the SD90 pilots would fit the MTH SD70mac? MTH never offered these with scale wheels and fixed pilots.