Originally Posted by A. Rosich

According to my trusted Diplomatic and Tourist Worldwide Sales Prices/Specifications/Options brochures (ref. years 1979/82/84/85) there was a Limited-slip Differential, M-B option code No. 256, but it was available ONLY for W126s and SLs. The option had to be ordered in conjuntion with code 601 (Special oil for rear axle with differential).

There was no limited differential available for W123s.

The only rear axle option codes available for W123s were:

Code No. 230: Rear Axle ratio 1:3.69, which by the way was mandated to be combined with option Code 646 (Tyres 15" tubeless). This extra cost option was only available for the 300D/230E and 280E models -sedans, wagons and coupes-

Code No. 212: Rear Axle Ratio 1:3.92. Code 646 had also to be ordered and this option was available only for models 240D/200 -sedans, wagons and coupes-.

I have a seen few W123s here with either of those options, they used to easily recognizable because of the 15" tires instead of the 14". But, as far as I know, I have never seen a W123 with a limited-slip differential fitted from the factory.

The limited-slip differential was a popular post-factory option. I have seen it installed on a Holland imported W123 (300TD) and a French 280CE. Several brands were available (as I remember seen several ads on european car magazines at the time).

Hope this helps to clarify the issue.