Can't find right collector seal for Rams Horn

[grubsster]

Hi all, I am at my wits end trying to figure out what "donut" goes in the collector of my passenger side rams horn exhaust. I removed them from a '66 Bel air but I'm unsure if they were original. I am also unsure but I think they are 2". I'm trying to find the donut and nuts that should go on these. I keep blowing out anything i install in there. I guess it's hard for me to explain so hopefully the pictures help. Engine is a 283 with Sniper 2 fuel injection '66 C10.

Thanks in advance...