The rear end tunnel is a tube with a pumpkin shaped indentation in the center which provides clearance for the drive shaft and the housing of the differential. It allows the rear end to travel up and down with suspension motion; it clears the differential housing by a maximum of three or four inches when the suspension is fully compressed. The rear end tunnel often forms the front of the trunk floor. It is attached to the wheel wells on each side as well as the floor pan and the trunk floor.