You also have to pay attention to the lower stud of the rear shock. It is oval in shape, and if you do not line it up correctly in the lower control arm you will not be able to tighten it correctly.

I changed the rear struts on a friends ML320 in about an hour. Did not remove the inner fenders or spare tire. Ran my hand up the frame rail to get to the nuts with a ratchet wrench. Not a pleasant job, but it was only an hour.