Has an AFL game ever ended 87-51?
Exactly once. On June 29, 1957, Melbourne beat Footscray 87-51, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 87-51 in league history.
That makes 87-51 the 3836th most common final score out of 6,607 that have ever occurred in AFL. One point away, 88-51 has happened 3 times and 87-52 has happened 3 times.