This manual covers Mercury MerCruiser GM V8 engines produced between 1998 and 2006, specifically the 305 CID (5.0L) and 350 CID (5.7L) configurations. These robust engines, known for their reliability and powerful performance, are designed for a variety of marine applications. The V8, Overhead Valve (OHV) design, coupled with water-cooled systems and electronic ignition, ensures efficient operation. Whether equipped with a sterndrive or inboard transmission, these engines represent a significant investment in marine propulsion, and this guide is tailored to help you maximize their longevity and performance. The scope of this comprehensive Repair, Workshop, Owner's Manual, and Parts Catalog provides essential information for maintaining and repairing your Mercury MerCruiser engine. It details routine maintenance procedures such as oil changes, filter replacements, and cooling system service, alongside advanced troubleshooting guidance. Technical specifications, including engine dimensions, bore, stroke, and compression ratios, are thoroughly documented. This manual is an indispensable resource for owners, mechanics, and technicians, offering the knowledge required to keep your engine running optimally and safely throughout its service life.