It was a Monday.
October 13, 1986 was on a Monday.
October 13, 1986 fell on a Monday.
May 13, 1986 was a Tuesday.
November 13, 1986 was a Thursday.
March 13 1986 was a Thursday.
June 13 1986 was a Friday.
September 13, 1986 fell on a Saturday.
13 October 1964 was a Tuesday.
13 October 1978 was a Friday.
13 October 1958 was a Monday.
13 October 1970 was a Tuesday.
13 October 1965 was a Wednesday.