From what I can find on line, it has three air tanks. Two between the frame rails over the front axle and the third about three feet further back, still between the frame rails and on the passengers side. If I were to go under to look at the tanks, I'd go in behind the passenger front tire.
What they did on my MH, a 2005 Fleetwood Excursion, is they ran three lanyards up to the front that you pull on to drain the tanks. They sit beside the generator on the passenger frame rail. You have too raise the "hood" to get to them
Gillig air tank clickyBill
