The very early Minis used the rubber U-joint drive couplings to eliminate harshness being transmitted to the passenger compartment. Over the years the rubber will separate from the metal sleeves and allow the driveshaft to rotate out of concentricity. Not only can this cause vibration, but it can also allow it to hit either the tranny case or, more often, the exhaust pipe. These are standard replacements with u bolts and nuts for one side only.

Torque wrench settings: Flexible coupling U-bolt nuts: 16Nm (12 lb-ft)