Quick check, engine off, have a couple adults sit on the rear with open rear tailgate, then start the engine. The rear of the car should rise back up to "normal" height. Typically "normal" is, I think, 12.5 inches measure straight up from the center of the star hubcap to the outer bulge of the fender lip. Check that against what others have posted.

After it has been running and is in a stable condition, unloaded, shut of the engine and then check the SLS hydraulic fluid reservoir. There should not be any dripping after a few minutes from the oil return line. If it keeps drip drip dripping, then the base pressure valve (inside the control valve) is leaking by, and the rear end will sag after left parked for hours / days.

Test drive, it should be a nice smooth ride over bumps, without a too much up/down and not stiff and bouncy.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC