I just picked up a new Proto 2000 UP SD50. Life Like put the horn (for some reason) on the cab. After looking at some prototype photos, I have noticed that is not the correct location. I want to move it, but am not 100% sure where the correct place is. On most modern locos, it is in the center of the section of hood that covers the actual prime mover, but on the SD50 photos I've seen, it seems to be farther back on the hood than that. If someone could clarify this for me it would be much appreciated!
...About here:
http://trainiax.0catch.com/upsd606024.gif
It's centered side-to-side, and is placed on a small "pedastal" a few inches high.
I have seen SD50s with horns on the cab, and I think their location just in front of the radiator fans is a UP modification that was later adopted by the loco builders.