After market replacement part for Upper Radiator Hose Connector?

That water neck is not a replaceable part even though it looks like it is. That is only available as part of the radiator that it is bonded with. They make that part, then apply glue to it and it is installed into the radiator. Because it's a common part it is molded as its own part then bonded into the various radiators that it fits and looks like it's replaceable, but it isn't.