Nissan Repair: nissan serena 2.3d constant 4wheel drive, dual mass flywheel, drivetrain components

Question
k plate does this model have a moving mass fly wheel i am experiencing knocking from 40mph to 65mph all other areas have been looked at with no fault

Answer
Stuart,

Yes, if original, it should have a dual mass flywheel.  If it is just thumping it is normal, as the car ages.  But, if it is actually knocking then I would be looking at a replacement flywheel.  The reason behind the dual mass flywheel is to dampen the shock loading of the drivetrain components.  Single mass replacement units exist and if you do not drive agressive the drivetrain components should continue to function as normal.