International Truck and Engine Corp. said it would allow its contract with the United Auto Workers (UAW) to expire at midnight Monday, which could lead to a strike affecting more than 7,000 workers at seven locations. The contract was due to expire Oct. 1, but negotiators had agreed to an indefinite extension. Either the company or the union could end the extension with 24 hours notice. International's parent company, Navistar, gave that notice Sunday."We regret that despite three months of intensive negotiations, including a three-week extension and involvement at the highest levels of both organizations, we still have not been able to reach an agreement to help build short-and long-term strength for the business," said Dan Ustian, Navistar president and CEO.Negotiations on a new agreement that would cover about 7,100 production, maintenance, clerical and technical workers began in July. The agreement covers workers at Navistar sites in Fort Wayne, IN, Melrose Park, IL, Springfield, OH, Indianapolis, Atlanta, Dallas and Baltimore.