Collector ? Flange ?

Those headers fit perfectly in any 67-74 A body.

To hook an exhaust to them all you do is get the same size pipe as the collector and expand it so it slips over the collector.

They make weld on tabs so you can use bolts to go through the tabs to hold the exhaust pipe on the collector.

There are several variations on the tabs. Pick the tabs that get you the most excited and use those.

This is the same header I use on my junk. They are a royal PITA to install and remove, but they FIT when they are on. And they make power.