Again! the only US cars(last 20 years) that had limited slip are the 560's & the 190E 2.3 16V. IN europe limited slip was offered on many cars. THE W123 chassis NEVER had limited slip.
Benzmac is correct, ASR didn't happen until 1991.
4-Matic came out here in 1990 & ASD came out in 1991 on lower HP cars & diesels.
With modifications the 16V limited slip WILL fit into a W123 chassis!! I have done several for myself & a friend.
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)