I called the same O'Reilly's and spoke to a different person who argued with me that a water neck didn't exist for my vehicle because it wasn't listed in his computer. When I asked him to look up water outlet instead, all he could find was a gasket. He told me he'd never heard of a water neck or a water outlet, and I quote " . . .and I work in an auto parts store, sir."
Reckon I'll just go to White's in Macon next time.