in the way to work yesterday, i cahnged gear and the car made a horrid noise then just stopped i had no drive at all, can still get all gears but no drive, no ive got the car in the air out side and when i turn the wheels the passenger side works fine turn the bot etc, but the drivers side just spins, i first though it is the diff thats let go which is a escort lsd unit, could it be anything else? what best to check before removing the box? thanks al