No. 80-1677. Argued March 4, 1982. Decided April 1, 1982. Roderick D. Gillum, Gen. Motors Corp., Detroit, Mich., for petitioner. Elliott Moore, Deputy Assoc. Gen. Counsel, Paul Spielberg, N. L. R. B., Washington, D.C., for respondent. Petition for review from the National Labor Relations Board. Before MARTIN, Circuit Judge, PECK, Senior Circuit Judge, and PORTER, Senior District Judge. Honorable David S. Porter, Senior United States District Judge for the Southern District of Ohio, sitting by designation