Has an AFL game ever ended 55-51?
It has. 55-51 has been a AFL final 4 times in 16,622 games. The first was Melbourne beat Richmond on May 12, 1928; the latest was Port Adelaide beat Adelaide on August 7, 2021.
That makes 55-51 the 947th most common final score out of 6,607 that have ever occurred in AFL. One point away, 56-51 has happened 2 times and 55-52 has happened 2 times. At one point the score disappeared for 93 years, between 1928 and 2021.