NORTH AMERICA - General Motors announced at its annual meeting on June 3 the closure of four truck plants employing 10,000 workers in North America. GM said it would stop making trucks at plants in Oshawa, Canada, and Toluca, Mexico, as well as at U.S. plants in Moraine, Ohio, and Janesville, Wisconsin. The announcement came at a time of falling sales of pickup trucks and SUVs and GM said its plans would…