FLINT, Michigan (AP) — General Motors plans to invest more than $1 billion in two Flint, Michigan, manufacturing plants for the production of the next-generation internal combustion engine heavy-duty trucks. Gerald Johnson, executive vice president, Global Manufacturing and Sustainability, said Monday that the company will build internal combustion vehicles throughout this decade, in addition to making electric vehicles. GM has a goal of building only electric passenger vehicles in the United States by 2035.