Thanks for your help. Spot on advice! The fault was in the joint - the spline was worn and tightening up of the splined joint had no effect. The joint has been replaced and the noise has gone. Great!he V6 cars have a splined joint to accomodate variences in shaft length. It should be clamped tight. Takes a 17mm socket & is accesable through the oppening in the bottom of the rear engine support.