Exhaust leak?

Last week a chirping sound started to come from my 289 2V '65 mustang. I asked around, and was told that it was probably the exhaust manifold gasket. I spent all of today taking off the manifolds and replacing the gaskets only to have the same problem, except it's much louder now. If I put my hand somewhere around the 2 or 3 cylinder exhaust ports, I can feel an air leak, but I don't know where it's coming from. Any suggestions as to where it may be coming from? Thanks, Oscar