Not all class A pushers will have all those items. Most probably will have similar items. "Jake brake" is a common term for some type of engine braking capacity. The original "jacobs brake" were solenoids that opened engine valves independantly of the camshaft timing in order to help slow the heavy truck. More common today are exhaust brakes which trap the exhaust in the engine instead to accomplish the same thing. Modern exhaust brakes don't have the same rat-a-tat-tat that the jake brakes of old had.
Air ride suspension can be seen by looking in the wheel well for a typically black, rubber cylinder aobut 10-12 inches in diameter. (some are smaller depending on the weight of the rig) Depending on the chassis manufacturer they will have one or two per wheel. Non air ride will have either leaf or coil springs visible in the wheel well.
Air brakes are more difficult to describe, but if you step on the brake pedal (with air in the tanks) when you release the pedal you will hear the exhaust of air underneath the rig.
Price will tell you the mid to upper end MH's, assuming you are comparing similar length and model year.
All things being equal you will find fiberglass roofs to be longer lasting and lower maintenance.
Ken
