RE: '63 TradeWind Manuals
You are correct that Airstream didn't publish Owner's or Service manuals for the '63 Airstreams. The first year for the Owner's Manual was 1964
. If my information is correct, it would be several years after that before the Service Manuals were published. Even in 1964
the Owner's Manual wasn't terribly specific about plumbing or electrical questions - - generic diagrams were provided that at least give some clues. As similar as the '63 and '64 models are, you might find a '64 manual helpful. During this time period, each coach was supplied with an envelope of manufacturer provided manuals for installed appliances and accessories - - often these manuals will be more helpful than the owner's manual in answering specific questions about an appliance.
Good luck with your plumbing project.