Ford Motor Co. and the United Auto Workers union have reached a tentative agreement on a local contract at the company's largest and most profitable factory, averting the threat of a strike. The union said last week said that nearly 9,000 workers at the Kentucky Truck Plant in Louisville would walk picket lines starting Friday if the contract dispute was not resolved. The tentative agreement addresses health and safety issues, ergonomics, the company's efforts to reduce the number of skilled trades workers and other issues, the union said.