Your father's full name is John Alexander MacDonald, born 26 Nov 1929 and died July, 1980.
He married Gloria Georgine Harter 12 Jan 1948. Gloria later married Guy R Seaton (18 Nov 1920- 24 Jun 1995, last residence Hot Springs National Park, AR.).
Gloria was born 18 Jan 1929 and died 15 June 2003, last residence Hot Springs National Park, AR.
One of Gloria's children is Jack Dale MacDonald, born Sept 1958, also of Hot Springs and Hot Springs National Park, AR. Not sure if he's still there, but try this first.
360 LAKELAND DR
HOT SPRINGS NATIONAL PARK, AR 71913