Nos. 73-1553, 73-1708 and 73-1852. Argued May 28, 1974. Decided June 20, 1974. Laurence J. Cohen, Washington, D.C., for petitioners in No. 73-1553 and intervenors in No. 73-1708. William M. Saxton, Detroit, Mich., with whom Robert M. Vercruysse, Detroit, Mich., was on the brief for petitioner in No. 73-1852 and respondent in No. 73-1708. John D. Burgoyne, Atty., N.L.R.B., with whom John S. Irving, Deputy Gen. Counsel, Patrick Hardin, Associate Gen. Counsel, and Elliott Moore, Deputy Associate Gen