I have recently converted my car from a 2.0L pinto to a 2.0L zetec engine and wondering if i can use the temperature sensor from the pinto engine and fitting into the zetec thermostat housing? it does screw into place but will the temperature guage still relate to the engine I.E when the guage is in the red the engine will be?

Sender is matched to gauge. As long as they stay together it will read the same as it did in the pinto. You will need to earth the sender body if it's a single wire as the zetec tstat housing is plastic. (Assuming you are fitting it there and not using a metal water-rail.