Pete -
When the time comes I'll post progress photos of the fiasco, er, build on the A&O web site. It would be relatively easy to hide a 1925S in the fuel tank since it is almost exactly the same length. The S0768 16-567 engine very rapidly drops to idle and has a good, throaty sound that just demands more bass. The file reminds me of a screaming Ontario Northland GP9 kicking cars posted to Youtube.
Here you can see the relative size of a 1931 compared to the under frame of an original RC 2R drive. No, I won't be modifying this one for the project. Of course the usual weight in the fuel tank will have to go, but there will be room in the sides of the tank for Cerrobend. I also have U-shape steel weights for 3R locomotives that Bill McClung gave me some years ago. The fake RC plastic frame stiffeners aren't the right profile (should be more of an I-beam) so I'll do a little faking there, and move them outboard to clear the speaker. How do I know? I photographed GW2233, an ex-ATSF GP7, while being scrapped (with permission, of course.)
In my narrow hood Overland diesels I still install the 1925S. Nobody has ever complained about the sound.
