Fiat Chrysler Automobiles NV will face a shortage of new products in North America over the next 18 months, especially hot-selling trucks and crossover vehicles, according to three sources familiar with the company’s plans. While the Italian-American automaker said it will bring three new sports models from Italy to the United States in the coming year, it plans to introduce only one all-new vehicle developed and built in North America: A redesigned Chrysler Town and Country minivan that is due next spring.