Welcome aboard. The Engine and Outdrive are Mercruiser. In the case of Brunswick boats (Maxum, Bayliner, Searay, etc) they use Mercury/Mercruiser engines, drives and outboards because they happen to own them as well. Otherwise, the boat manufacturer makes the hull and the deck and assembles them, while everything else is third party. This is the case with ALL boats. You are more than likely actually looking for the Engine and Outdrive Service Manual, which is sold seperately. Information like maintenance is not in the boat manual, its in the engine and outdrive/outboard service manuals.
As a result, the boat manual has limited information. Try a search on MANUALS here on the site. We have a space where many are posted.