It looks like the left rear shock absorber on my '82 300D Turbo is leaking. Today when I came back from the other side of town I noticed that something was dripping from behind the left rear wheel. The fluid smells like diesel, but it can't be since it's coming from the shock absorber. I put one of those throw away plastic cups under there and now there is about 1 cm of fluid in it. Can the shock absorber leak this much fluid?

I understand that replacing the rear shock absorber is not that hard. Is that correct? Any help is appreciated.