I'm going to speculate that the ears got broken off from someone trying to tighten them until they would seal. Fact is there is an underlying design problem. OE manifolds have a rounded "half donut" type of surface for the headpipe to attach to. Repro's have a tapered style. Most repro headpipes have the correct "half donut" sealing end made on them, so if you connect them to an OE manifold you will not have an issue getting them to seal. With Repro manifolds, good luck getting them to seal up to the headpipe!