Okay. The second question in my original post was poorly worded.
Here's the corrrected question. I have the two supposedly matched exhaust manifolds and y-pipe from a '76 to '80. When I look at the mount of the y-pipe to the RH manifold, everything lines up and the little "donut" fits between the two perfectly.
But on the left hand site, the exhaust manifold is domed outward. The dome fits in the receiving end of the y-pipe, but there is no place for the donut.
Is this correct? Would this cause exhaust leaks or excess noise?
I'm actually going to run duals, and SQUAREROOT has me thinking again about headers. Nonetheless, I ask the above question since I want to know how these work.
Thanks everyone for your great responses and for indulging me on this last question.
Pics attached.