Keith: My coach is a 98 Patriot 37' and does not have air brakes. So, my brake system happens to be hydraulic over hydraulic (yes - this is not a typo) and is not air over hydraulic and of course it had no air dryer either. I have since added a air dryer (a great investment anyway) which totally solved another problem of the ride height valves failing. Without the air dryer, I had water every day to and had to drain out of the tanks with the manual purge valves. Now with the air dryer i can drive 3000 miles and virtually no water comes out of the drain valves.
To the best of my knowledge, there were not any air or brake diagrams produced for the 1998 models but remember that mine is different. If you would like to call me maybe I can answer some of your generic questions. It was only 2 years ago that I had to replace my brake switch and it was not located in any "user friendly" location.
Larry
