Visteon Corp., the nation’s second-biggest auto parts supplier, plans to close three plants and put six up for sale under a restructuring plan. The plan could affect up to 23 of its facilities worldwide. It plans to close a plant in Buffalo in the third quarter, although about 70 customer service and engineering employees at the Buffalo plant are expected to keep their jobs. Visteon has been hit hard by production cutbacks in the ailing domestic auto industry, which is struggling with rising health care-costs, sluggish sales and declining market share to foreign car makers.