Has an AFL game ever ended 142-51?
Exactly once. On June 10, 1967, Essendon beat Hawthorn 142-51, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 142-51 in league history.
That makes 142-51 the 3836th most common final score out of 6,607 that have ever occurred in AFL. One point away, 143-51 has happened never and 142-52 has happened 1 times.