The seals in these water outlets wear out just as any ohther part on a 10+ year old vehicle. The one I purchased from Autozone fit perfect. Please note, this one has an opening on the back side with ability to add a small hose for a different car's applications. My ford focus does not have this this hose, though the part comes with a small plug and o-ring that seal it perfectly. Would highly recommend if you are losing coolant or see spray of coolant on surrounding parts, firewall or inside hood. Check your water outlet. Not difficult to install either. Had to remove the battery and battery box, pull a couple of hoses and the three connectors to the ECM. Bolts right in and (knock on wood) seems to have fixed the problem.
What kind of vehicle do you drive? 2010 Ford Focus SEL