Yep, I'll post a link when I get it scanned. It would be possible to add "manual" ASD, triggered by a switch on the dash. Or even a fully manual trigger with a hand hydraulic pump (saw that done by a guy in Europe, I think). But to retrofit the full ASD system, that would most definitely be a challenge (and probably quite expensive). You would need the ASD brain box, wiring harness, speedometer, and all the hydrualics & valving. My '93 300D has factory ASD, btw. However, the ASD still uses the standard ABS system with a single rear speed sensor... only ASR has the dual rear sensors (my V8 models have ASR).
While I really like factoy ASD, I believe it would be too difficult retrofit, unless you had a complete ASD donor vehicle to snag ALL the parts from. Even then, I am not sure what the challenges would be. All I wanted was to eliminate the "one wheel peel" on wet or dirty pavement, and plain LSD has cured that (at least with fresh clutch packs installed). If you buy a used ASD diff, it's almost guaranteed to need new clutch packs.
While converting to plain LSD is not simple, it's much easier than attempting a full ASD retrofit. The cost to convert to LSD is at least $750, plan on more like $1000, including the new clutch packs, seals, fluid, etc. Those numbers do not include labor, that's parts only. I don't know what it would cost to do ASD but I would figure at least $300 more plus a LOT more labor.