Has an AFL game ever ended 82-51?
It has. 82-51 has been a AFL final 3 times in 16,622 games. The first was Richmond beat Sydney on May 14, 1921; the latest was GWS beat Fremantle on April 14, 2018.
That makes 82-51 the 1534th most common final score out of 6,607 that have ever occurred in AFL. One point away, 83-51 has happened 5 times and 82-52 has happened 2 times. At one point the score disappeared for 84 years, between 1934 and 2018.