to fit to fiesta you would have to strip it bare and put on your exhaust, inlet, flywheel and clutch (mondeo is dual mass and mtx75 fiesta is ib5) also change thermostat housing to yours as mondeo is ecu controlled. you would have to also put on your oil cooler off the st as the mondeo doesnt have an oil cooler! other than that it should fit. Just put the mondeo engine in my Mk5 fiesta and swapped it to run ST parts.