Regarding the Craftsman 3 ton jack stands pictured earlier, they work fine on my 300SD, so I would imagine that they would be tall enough for your 240d.

On the subject of jacks, I am tight on space as well, but I find that a short wheelbase floor jack is extremely useful, especially when having to lift the whole front or rear end to do work.
It also is fairly compact, once you break the handle down, at least.
The steel version that I bought from Sears is a bit on the heavy side to lug around, but tossing it in the trunk isn't too much of a problem.

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-Josh
Testing the cheap Mercedes axiom, one bolt at a time...