Do you have a picture you could post of the engine compartment?
My first MB was an '84 500sel Euro and it had the 4 corner hydro-p suspension. I never did get around to replacing the nitrogen spheres and the car drove really rough (almost as tho, I had too much air in the tires).
I don't know the difference in how each engine bay looks but I do remember that my reservior was up near the front drivers side just behind the headlight. Also you could see each nitrogen sphere in each wheelwell.
The whole system is very expensive to maintain. The hydrostruts cost an arm and a leg to replace. I had just 1 replaced and it cost me $800
