Congratulations! The Argosy manuals were pretty basic. I don't know of anybody who has put one online yet. At least it gave you the payload capacity.
Here is some boilerplate info copied into this post:
Q: I need an owners and service manual for my Airstream. Where can I get one?
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.