What year models had ADS? And how good is it?
 

Im looking for an ASD differential for a custom project and I'm wondering if anyone knows what year models used it? Was it always optional or did it come standard on any year/models? Aside from looking at the diff how can one tell if a car has it? From people who have experience working on the system or driving a car with it, what are your thoughts? Do the clutches in the diff wear out? I wouldn't be using the electronic aspect or the accumulator, just the diff with a manual pump to engage it. Thank you!

A partial answer is W126 300SE 86-91. Seems to have been optional. The instrument cluster has an indicator that illuminates when the clutches are applied.
Note: The ASD device was used with diffs with 185mm ring gears. The larger diffs (210mm) were equipped with ASR.

The W140 S350 also was optionally available with ASD; 210mm diff, 2.82:1

I've come up with evidence ( shop manuals ) that the 94 C230 ( W202 ) could come with optional ADS. After that, ASR was an option. I'd expect sunny climate cars never got ASD / ASR .