Congratulations on the Suncrusier. You're now going to start the fun of familiarizing yourself with the new rig
As far as a air fitting, most chassis are manufactured with an air manifold under the front hood of the motorhome. This manifold is installed by the chassis manufacturer for the body builder to use to connect their accessories onto.
Try looking underneath the hood and seeing if you can trace the air hoses from your air horn solenoid if you have one. That hose, along with several others will go to a distribution manifold which is usually just a metal block with multiple ports with plugs in them. If you can't find the manifold easily, you can try following the hoses from the air storage tanks.
I think my air manifold has 1 hose feeding the manifold, and about 4 hoses coming off. There were still quite a few unused ports, so I added a quick connect air fitting to one of them.
I carry a couple air hoses with matching quick connects in the motorhome. I havn't ever needed air on the road for the motorhome tires yet, but I sure have made quite a few kids at various campgrounds happy when they find flat tires on their bikes
Joe & Shelly, Justin, Tyler, Alyssa | Butler PA
2008 Tiffin Allegro Bus 43QRP|Cummins 425|Honda CRV