It's the West Adelaide bench. That's Jack Oatey (West's coach at the time) doing the splits.
The offending goalpost was chopped down later that night by some West Adelaide players (including Neil Kerley) who jumped the fence into Adelaide Oval. It ended up on the BBQ at the West Adelaide wake and what was left of it after that was hung in either West's clubrooms or behind the bar in a pub in West's district. Sorry, can't remember the exact location. A classic SANFL legend though.