Gary, Mark Twain did not have any shop manuals so to speak. There are some really good repair manuals available from companys like Selock, or Chiltons that cover repair and rebuilding of outboards and all stern drive makes. You can find them at some auto parts stores or you can find them on line from some of the Marine stores like Boaters World or Overtons etc. If you live where there is a local marina or boat repair shop, they can get them also. I think they are around 15 or 20 bucks. There is also a few websites you can go to to buy parts that have excelent parts breakdowns of sterndrives. There is Seiler Marine, Action Sports, and Green Bay Parts World to name a few. Hope this helps
Happy Twaining
Dave