Hi John,
You sort of got me there, but the GA8 uses a body mounted traction motor with shaft drive to the trucks. David's idea of converting an SD to 3' gauge would have required truck mounted traction motors, of which EMD only made a very few. At 800 horse power, a GA8 would be about twice as powerful as the C&TS #19, so no need to convert an SD40 anyway! EMD came out with an improved unit, the GL8 which does have truck mounted traction motors, but was only made in meter and larger gauges.
I'm guessing the IRCA (later FEGUA) diesels have all gone to scrap, since the railway is gone but 21 went to Mexico. I wonder how many of them are still around?
Michael Allen