Collector ? Flange ?

I truly hope that you are both right. I did mention that i havent worked on small blocks, and its more than possible i am wrong.
I was just going by 30 years experience with a pair of big block supercomp adjustable's that look just like yours.
Edit: btw, what i did on my street exhaust for mine was.... i made six pairs of four bolt square flanges (i also had a custom set for another car that also didnt have flanges) because four bolts were easier to make. I made several seta of dead soft aluminum gaskets to match, and used one set on each header, and the last sets just after the mufflers, so i could drop the tailpipes or the muffler section if i wanted.
If i did it again today, i would simply buy flanges from summit or jegs, and weld them on.