Saginaw Metal Casting Operations is an automobile engine foundry plant in Saginaw, Michigan. Opened under GM management in 1919, the factory produces engine blocks and cylinder heads for General Motors vehicles. The factory currently occupies 1.9 million square feet on 490 acres. The location was originally the Marquette Motor Company until acquired by William Durant in 1909 when the car was discontinued in 1911. During World War I, it was used to manufacture mortar shells for the US Ordnance Corps, then was repurposed for engine block casting when operations at Northway Motor and Manufacturing Division ended in 1925. Historically in September 1927 it was known as the Chevrolet Grey Iron Foundry. In the past when it was called GM-Saginaw Product Company (SPC) a cloverleaf casting symbol m