6.9 owners would be familiar with the full hydraulic system that , apart from struts and valves, plus some other components, incorporate five Pressure Cells - four for front and back, plus a Master unit that replenishes the system if there is a drop in the suspension level.
I recently required five units to be fitted to a car I had in my care. Endeavouring to purchase locally, I was unable to locate any units - neither front nor back. I did have three front units on hand which I purchased...