Ford Motor Co. will announce Thursday that it is separating its Visteon Automotive Systems parts unit in a distribution to shareholders, creating the world's third-largest automotive supplier, peoplefamiliar with the plan said. The world's No. 2 automaker will detail the timing of its plan make Visteon a stand-alone company and specify the number of Visteon shares to be distributed for each Ford common share, the people said. The transaction would be structured similarly to the April 1998 spinoff of Ford's Associates First Capital Corp. consumer finance unit, the people said.