You might want to try Captain Ron's http://www.captainrononline.com/index.htm Send him an email and even if he doesn't have what you are looking for he may be able to recommend an alternate source.
BTW........I think wiring diagrams in owners manuals is a relatively new thing.
A copy of an owners manual covering all boats up to the 26' models built from 1966 to 1981 is now available. It is a laser printed copy of the original with a heavy paper bond cover just like the original. When you order it, you will also get an electrical diagram.