I looked at a few photos of a deskirted HO model, and I couldn't find it.. so.. its very well hidden.. (somewhere in front behind the pilot skirting?)..
So.. hidden enough to not worry about it?
I did find an air horn on the front engineer side just above the pilot where the bullet nose meets the pilot and steps.
Earlier models look like they may have an air whistle in the same place.
Where is the bell on the T1?.. likely same place..?
NYC Niagara had the bell on the engineer side inside the front pilot.