https://www.rugbyleagueproject.org/seasons/nswrfl-1979/round-11/canterbury-bankstown-vs-manly-warringah-sea-eagles/summary.html
MW: 20. Cray (I think). It can only be Cray or Meredith. Cray was a late replacement in the side for Ian Thomson & Meredith replaced Gartner in the game. All the other numbers should be the same as in Big League.
Source:
https://www.youtube.com/watch?v=CJA41k6SiFk
see 10:35
Vautin scored only 3 tries against Canterbury in his career & only 1 of those games had Hartley as the referee who you can see in the video, so it has to be this game.
I think #20 is Meredith, Steve Cray was a pretty big guy.
I don't know the face of either player, so I will take your word for it.
I contacted a friend who is a Manly expert - Eric the Eagle on YT. He said that it is definitely Meredith & sported a beard in a game a couple of weeks earlier. Confirmed!