not sure what goes on the upper, but on my exhaust flare junctions (the ones with the clamps like the lower left in your picture) i used a gasket material that is made for exhaust (not paper much thicker) and has a wire mesh in it, buy it in sheets (4x6 in. is what my small motor repair shop had on hand) and used the old one as a template to cut the new one. it just sits in the flare and deforms into a more bell shape when the clamp is tightened. after two disassembly since install they are still holding up and were re-used each time.