Seventy-four-year-old Barbara Walters, who only last year reduced her workload at ABC News by pulling out of the weekly primetime news magazine 20/20, has been enlisted as a part-time fill-in for the critically injured Bob Woodruff on World News Tonight. She has also agreed to spell Charles Gibson and Dianne Sawyer on Good Morning America on days when they, too, fill in for Woodruff. Wednesday's New York Observer noted that the scheduled appearance of Walters together with Elizabeth Vargas on WNT Wednesday night marked the first time that two women have ever co-anchored an evening network newscast.