I have a 1986 190E 2.3-16 valve with 80,000 miles. I have had noticeable looseness in the drivetrain for a long time that appears to be in the differential. When the car was up on my lift, I turned each section of the drive shaft and observed that with the rear wheels blocked, I could turn the differential input shaft perhaps 10 to 20 degrees of rotation (rough guess). At each end of the rotation there would be a "clunk" sound.
How much slop should I observe in the differential? It is annoying, because the car suffers from some driveability problems (light missing, surging) and the loose differential seems to magnify the problems.
How much trouble is it to tear down the differential and check the setup?? Is there an adjustment on gear mesh?