Ford Motor Co. plans to add 6,200 union manufacturing jobs and invest $3.7 billion into plants in Michigan, Ohio and Missouri, as it looks to expand vehicle production and prepare for coming labor talks. The multibillion-dollar investment will go to retooling factories to build newer versions of gas-engine models, such as the Ford Ranger pickup and Mustang sports car, the auto maker said Thursday. Ford also plans to expand production of its electric F-150 Lightning in Michigan, as well as add an all-electric commercial van to its assembly factory in Missouri.