On our present coach it came from the factory with an air valve and hose installed to put air in the tires. On our previous coach, I installed an air connection for a hose on the distribution block in the front of the coach.
Freightliner installs the distribution block for the connection feed of air horns and hoses for airing purposes.
You don't mention what chassis/coach you have, but I am guessing that it is a Monaco with a Roadmaster chassis. I would think they do the same as Freightliner.
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