I used to pal around with a friend that had a 1939 Buick, and he had the original jack, although I never saw him use it. Because the car was all original, what he did was keep the original jack nice and clean and oiled, etc, and held in it's proper place in the trunk, for "looks" sake. Then, because the trunk on a 39 Buick is somewhat violently cavernous, he had a small hydraulic jack in the car specified to the car's weight that he would use if something happened.
Since you can fit several bodies in the trunk on most MB's, I was going to do the same, although I got my 75 450SE used from a front yard so I have a little scissor jack and that's it. Once up and running, though, I will have to find an original.