William R.Chilton;51;of 237 Harry Truman Drive;Upper Marlboro;Md.;died Sunday;March 18;1990;in his home from an apparent heart attack.  He was born Sept.17;1931;in Belle Vernon;a son of the late Raymond (Buffalo) and Hazel Chilton.  Mr.Chilton was a graduate of Bellmar High School and served honorably in the U.S.Air Force.  After leaving the service he made his home in Maryland.  He is survived by three sisters;Wanda Colquitt of Columbia;Md.;Gwneath Tartt of Landover;Md.;and Eleanor Chilton of Largo;Md.;a brother;Wayne Chilton of Largo;Md.;and a host of nieces;nephews and cousins.  Friends will be received at the Beverly C.Draper Funeral Home;608 Sixth St.;Monessen;Thursday from 7 to 9 p.m.  Funeral services will be held Friday at 11 a.m.in the funeral home with the Rev.Jesse Frost of Mt.Zion Baptist Church of West Newton officiating.  Interment will be in Belle Vernon Cemetery.  The Beverly C.Draper Funeral Home is in charge of arrangements.