They are simply bolted to the frame!
It is a really quite simple. Support the Airstream on 4 jack stands in the proper positions, remove tires. If you have two or more people, simply put a floor jack under the axle to be removed, and some blocks under the hub/drums to maintain balance. Disconnect electric brake wires. Remove the 4 bolts, and lower the axle. Very simple. I did mine with no help, but removed the hub/drums and brake plates to make it easier to handle the axles by myself.
2003 GMC 2500HD 4X4 D/A Ext. Cab
Propane Powered Honda EU2000i
Lots of Hot Sauce!
Air # 283