Airstream manuals, parts books, free
In case you have not found it, Airstream.com has some amazing resources.
Under the main page settings look at Service. Hover there and you will find Document Archive and Manuals.
Under Document Archive you can find a lot of interesting history information on years from 1947 and up. Just click and be amazed.
Under Manuals you will find a lot of downloadable manuals for many years of Airstreams. Then the treasure is the parts manuals for relatively recent years. Many of the parts manuals have diagrams of the parts as well as their numbers, and you can see how things were built in many cases.
All of it is free. And worth every penny!