Crestar Financial Corp. of Richmond, Va., which Atlanta-based SunTrust  Banks Inc. bought Dec. 31, has named its third chief financial officer in   less than a year.   
David F. Dierker will become CFO on July 1, taking over from James D.  Barr, who succeeded Richard F. Katchuk in January. 
  
Mr. Dierker, 41, joined Crestar in 1996 and is currently corporate  strategic financial officer, in charge of planning, budgeting, and earnings   management. He is an executive vice president.   
Mr. Barr, 56, is scheduled to retire after 25 years at the company. When  promoted to CFO he was treasurer, controller, and an executive vice   president.   
  
Mr. Katchuk, who became CFO in 1995, left the company to assume the same  title at CarrAmerica Realty Corp. in Washington, a developer of office   properties.   
John W. Spiegel is the chief financial officer of Crestar's parent,  SunTrust Banks.