The compensator is a pretty neat device which is totally self contained. When they failed, many cars had them replaced by a spring since it was much cheaper. Conversion back to the compensator is easy... just install!

The later self leveling suspension (first available on the /8 W114 W115 cars I think) had an engine driven hydraulic pump, nitrogen spheres, etc. This system is found commonly on wagons (123, 124, 210, etc), 6.9s, and option on several other models.

Jaime