Are you asking about the location of the air brake pressure guage sensors? Just want to make sure our terminology matches before sending you in a wrong direction.
If yes to what I asked... they are on the underside of the coach on the left front corner. Mine are directly above the steering box. If you basically sit up once under that corner and look up you should see them stacked one over the other. It's probably about the location where the brake pedal is located but outside the firewall.
This is where they are on my 2001 Spartan Mountain Master chassis. I should know, I just replaced them both.