Unless you have a very special 380SEL, it doesn't have levelling suspension. Is there a reservoir with hydraulic fluid in the engine bay?
Lots of discussion on 126 sag in the archives. I never tire of telling folks to check the subframe mounts but a lot of people are content to put spacers in the rear springs.
Are you an allpar.com guy or did the merger mean MB and Mopar forums are now joined?