Mercury engine parts have special serial numbers found on the under-housing of the specific component. The engines themselves used specific casting numbers, which are embedded in the steel or iron blocks of the engine.
Part numbers are specific to the make and model of a vehicle. Some vehicles share the same part number, which can help boost the availability of a given part. Users can use part numbers to search for replacement components by using an online parts directory. They must input the exact part number found on the engine component into the database's search engine, such as the one found on AC Delco's website, which will then turn up any available parts for sale.
Mercury is a sub-division of Ford and in the early automotive years shared many of the same engine block numbers. The bottom and top half of an engine had a number cast into the metal. These cast numbers acted like the serial numbers found on a automotive component and included additional information for what vehicle the engine belonged to.
Earlier cast numbers from Mercury vehicles from the 1940s used a number before a letter, like the 59A engine for example, while later variations included an 'M' before the rest of the cast number.