Enthusiast owned and old school maintained example,  I currently own 3 other W126 chassis Mercedes, time to thin the herd.  In addition to 3000 mile oil change interval,  transmission was fully serviced, power steering, cooling system  and SLS systems flushed.  a Pretty loaded for a US Spec 560.  Options include rear sunshade ( motor works, needs nylon cable replaced), automatic slip regulation (ASR).    Sunroof slide and tilt work as designed.  Cruise works as does the often maligned  and optional ASR.  SLS rear suspension is fully operational. During my tenure which covers 10 years and approximately 35k miles all belts and idler pulley were changed as were all 8 fuel injectors, air tubes, MAF boot ( under the fuel distributor assembly), all 4 rotors and pads although there is a pad sensor that’s illuminating the dash light.  Washer nozzles and reservoir, rebuilt SLS pump and accumulators and a custom thicker rear sway bar with new links were fitted.  Oil level sensor has been changed. Front suspension components including guide rod bushings were replaced along with rear differential mount and rear subframe bushing mounts  All climate control pods were changed and the system is fully operational with 45 degree vent temp in AC mode.  System is charged with envirocool alternate to R12.  Rear seat mechanism was rebuilt and the rear seat is operational and is heated as well as the front seats. A remote lock was added and is operational.  The system taps into the vacuum operated door lock pump in the trunk.  Additionally, a terrific Bluetooth continental brand radio was fitted. ( I liked the radio for its period correct color and appearance )  Prior to my ownership, timing chain service was done at 140 or 150k miles.