John W. Peavy is leaving his post as CIO of the $75 billion Teacher Retirement System of Texas, Austin. Mr. Peavy was not available for comment, but sources said he wants to return to Dallas and resume teaching and consulting. Spokesman Howard Goldman confirmed Mr. Peavy "has advised us of his plans to leave the agency and that his departure was "imminent. Jim Hille, director of international equities, will serve as interim CIO. Trustees will discuss procedures for naming a new CIO at its June 27-28 meeting.