To be more precise:
The "Self-Levelling Suspension", or extra code number 48/0, was fitted in the late eighties as standard equipment to all T-series cars (wagons), the 190E 2.5-16, 560SE, 560SEL and 560SEC.
Then, it was available in Germany as an option to ALL cars (W201, W123, W124, W126) for D.M. 1,105.00
For a selected few models, an different option, called "Self-Levelling Suspension with stiffer springs and shock absorbers", code number 48/5, could also be ordered for D.M. 1,170.00
Finally, a more sophisticated system, which actuated on both axles (not only the rear one as the self-levelling suspension), called Hydro-pneumatic Suspension with Automatic Lowering System, code number 215, could be ordered as an optional extra for an additional D.M. 6,025.00 for the 420SEL, D.M. 4,930.00 for the 500SEL, and D.M. 3,830.00 for the 560SEL.
Mercedes-Benz also offers in its optional equipment list a long and very complete list of options to fine tune the suspensions according to the customers needs (including stiffer springs, lowered suspensions, and even raised suspensions set-ups for countries with extremely bad roads).
The afformentioned 450SEL 6.9 came standard with a former system similar to extra code 215, although, as many owners and mechanics know, is a very sophisticated and expensive system to repair (and it will fail, sooner or later).
The more simple self-levelling system tends to be more reliable, although, the dealer tells me that there is higher failure rate on 123 wagons than 124 wagons. The system on 126 sedans, if not serviced properly, are sure to fail.
If you are buying a T-series (wagon) or a sedan equipped with this system, be sure to check for leaks on the strut, the accumulators, and/or pump. Any repair would jump easily into the thousands!
Just my 2-cents worth!
[This message has been edited by A. Rosich (edited 09-30-2000).]