Choosing a reliable used engine is a practical way to restore performance without the high cost of a new unit. Engines supplied by Moon Auto Parts are inspected for mileage, condition, and operational quality to help ensure dependable results. The Grand Marquis is known for durability and smooth driving. For many vehicle owners, a 2004 Mercury Grand Marquis used engine from Moon Auto Parts offers a balanced solution between performance and affordability. Many available units, include a 4-year/40,000-mile warranty along with free shipping to U.S. commercial addresses, helping buyers secure long-term reliability while simplifying the engine replacement process.