The only thing I see under the pedal is a "plunger" that's inside of what appears to be a rubber donut. That assembly is bolted to the floor where it connects to an air valve on the underside of the floor.
I had aired down the truck to get a better look at what's under the pedal. Odd thing was that the cruise control set switch was very lazy increasing engine speed in order to get air pressure back up. Now, when I turn off cruise, engine rpms do not drop. Another way to turn off the cruise has been to depress the clutch pedal. That method no longer works. Are cruise control and brake lights somehow connected?
I think brake light switch is located in your dash where your gauges are and it works by air, you press a pedal and you trigger that switch. Google how it look like. When you press pedal you can hear it clicks each time you press. If not then it got stuck in one position.