WHEN GOING ABOUT 35 MPH THE CAR WOULD VIBRATE. SOMETIMES IT WOULD STALL AND THEN SLAM INTO GEAR. NOW THE CAR STARTED GRUMBLING AND I BELIEVE THE PROBLEM IS THE POWER TRANSFER UNIT.. THE CAR WILL DRIVE FINE WITHOUT THE DRIVE SHAFT BUT WHEN THE DRIVE SHAFT IS IN YOU CAN'T GO OVER 5 MPH AND THE CAR WILL START SHAKING AND MAKING A LOUD GRUMBLING NOISE.. LIKE WHEN YOUR GOING OVER THE RUMBLE STRIPS ON THE SIDE OF THE ROAD THERE IS OBVIOUSLY A PROBLEM WITH THESE AND HOPEFULLY FORD WILL FIX IT.. *TR