I dont have the truck anymore . Take a look at this link
http://www.holley.com/HiOctn/ProdLin.../f4201HKR.html
Here is exactly what they look like when you weld them as I am talking about . You can see it perfect in this link .
http://www.holley.com/HiOctn/ProdLin...f11030HKR.html
You can kinda see the flanges I am talking about . There is not that little flared ring that the collector rotates on . You weld it on the side opposite of the flared ring and then grind that ring off . Make sure the flange is straight (flat) first . On headers with the rotating flange , the only thing that the gasket seals on is that little 3/16th's inch flare . That is why they blow out. This way the entire flange clamps the gasket since they are the same size .If anyone has a closeup of a Super Comp, and can post a picture of the collector flanges , it would show you exactly what i am talking about since that is where I got the idea . Frank