ML/MN Tritons with the "easy select" transmission (Identifiable by a two-piece tailshaft) are renowned for developing a drive line vibration on take off. This vibration is caused by a combination of the short tailshaft length and the difference in angles between the universal joints and centre bearing. Fitting a 22mm tailshaft spacer on the diff side of the tailshaft reduces the severity of this vibration. It doesn't always eliminate the vibration completely, but does help reduce it and takes pressure off the centre bearing.
Vehicles with the "Super Select Manual" or Automatic transmissions do not suffer from the same vibration. These vehicles have a one piece tailshaft from factory.