Fleetwood's original manual, while having a lot of information, is not technical or specific enough regarding "systems", wiring, or schematics. Fleetwood's (earlier) policy was "10 years" for saving technical drawings and blueprint-type info. Still, your best place to start is to call Fleetwood and ask what they may have to send you.
I used to own one, what do you need to know, I might be able to help. The Manuel that came with it was no help, but there was a Manuel by the manufacture on each item, like Ref, Mirowave, Ice Maker etc.
check threads from a couple of months ago, someone did post about Southwind Manual.
David
1997 Fleetwood Southwind 37Y / Ford 460 / Power Platform / Tag Axle
Our Crew: (1)Yorkie, Twin Japanese Chins, Toy Poodle, Chihuahua, and last, but not least, their "MOM", my co-pilot and wife.
Buick Regal
Ford Taurus
Proudly served, USAF 1959-1963
we purchased an 86 pace arrow. called fleetwood, they registered us as the current owners and were able to provide us with the "as built" drawings for the electrical (12v and 120v), plumbing and propane lines at no charge.