Mike:

I have Air over Hydraulic on my 98 Contessa.  PO installed the M&G system, so there is now an air connection at the hitch.  Go under your coach at the wheels and look for the rubber air brake bags.  You won't find them in the system we have.  If you find them, shouldn't make any difference, you can still get the same air to your M&G at the hitch.