No. 24873. Argued March 7, 1972. Decided March 30, 1972. Mr. Thomas E. Silfen, Atty., N.L.R.B., of the bar of the Supreme Court of Illinois, pro hac vice, by special leave of court, with whom Messrs. Arnold Ordman, Gen. Counsel at the time the brief was filed, Dominick L. Manoli, Associate Gen. Counsel, Marcel Mallet-Prevost, Asst. Gen. Counsel, and Glen M. Bendixsen, Chief of Special Litigation, N.L.R.B., were on the brief, for appellants. Mr. Stanley Lubin, Detroit, Mich., for appellee. Appeal