CSS Analytical can upgrade your older HP 5971 and HP 5972 with a 10kv High Energy Dynode (HED) just like the modern Agilent 5973 MSD and Agilent 5975 MSD.  More signal, more sensitivity, lower Electron Multiplier voltage.  Simple upgrade.  Priced right.  Make your HP Agilent 5972 (and HP 5972) MSD more modern and up-to-date and live many more years.