Has an AFL game ever ended 83-21?
Exactly once. On August 7, 1920, Melbourne beat St Kilda 83-21, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 83-21 in league history.
That makes 83-21 the 3836th most common final score out of 6,607 that have ever occurred in AFL. One point away, 84-21 has happened 1 times and 83-22 has happened never.