Welcome to the Forums and the world of Vintage Airstreaming!
Startinging to keep a history on the unit and looking for specifications and require a manual with pics and such.
There are two means of acquiring the manuals for which you are searching. One is to watch E-Bay, where you will often find owners' manuals as well as service manuals being offered "For Sale" - - the one thing to be aware of is that Airstream didn't start publishing service manuals for its products until 1972 - - your 1971 coach is likely similar enough to the 1972 models that much of the information would apply to your coach as well.
The second possibility would be to obtain copies (photocopies of the original documents) from Secretarial Services as follows:
Q: I need an owners and service manual for my Airstream. Where can I get one?
A: The first owners manuals were published in 1964. Prior to that, the owner received a brown envelope containing parts lists and other helpful information on the accessories in his trailer. The VAC has started making these available in the Members Archive section. A service manual with instructions for performing service operations did not exist until 1972.
You can get photocopies of owners manual (1964+) and service manuals (1972-1986) from:
Helen Davis Secretarial Services
PO Box 484 Sidney, OH 45365
Prices are about $33 and $70 respectively. After 1986 the Owners Manuals included available service information.
*The above information is quoted from: http://www.airstream.net/FAQ/FAQ_3.html#Manuals
Good luck with your Excella!