Coming down from the exhaust manifold, you have the first sensor (I have forgotten the name), there is a spot where the short pipe from what I think is called the middle muffler connects to that flange looking area. Mine has come loose there and it does not appear to be a weld. Does anyone know what that is and how it connects?

 

Are you talking on the STOCK exhaust ? Just below the O2 Sensor?

 

at the lower end of the peice with the upper sensor (02?) attached for the stock exhaust

 

Thats a flange there is a gasket and two bolts with nuts that bolt thru it