my st170 was leaking from the clip in plug on the bottom of the housing is it not just this thats leaking on yours?cost just under £10, i only noticed it cos there was water staining on the bellhousing of the clutch, also earlier zetecs were plastic too, not sure bout the very first ones though but i know my 97 model escorts were plastic and have different sized sensors on top with different connectors compared to later escorts but the focus may all be the same, good luck with it mate