What's Missing From My Toilet (Leaking)

So I bought this toilet used quite some time ago and never got around to testing it out until yesterday. When I did water sprayed out from the area between the tank and the bowl. It looks like I'm missing some type of rubber washer that goes between the tank and bowl. If that's correct how hard is something like that to find?

TIA.

Did a little searching and it looks like I need a tank-to-bowl kit, or at least the rubber washer from one, but I still don't know if finding one that fits this connection for this American Standard toilet will be difficult or not.

Fluidmaster will have the standard foam rubber washer for your American Standard tank.
You have a 2" flush valve.
Take the Teflon tape of the threads of the fill valve too. You don't need tape with the rubber seal on the supply line.
Kind of like putting diapers over pants. You're already "covered".

Hey, I didn't do that! LOL. It was like that when I got it Terry.

Thanks.