The L stands for the long wheel base in the world of the S class. So an SDL would be a long wheel base S class diesel. There are 6 extra inch's added to the wheel base and you know it. The SDL isn't the best city/parking garage car.

Their were a lot of updates to the W126 from 85-86.

A W126 is a W126 it doesn't matter whether you are talking about a 560SEC or a 300SD. They are all pretty simple to work on and user friendly.

The SD's make a sweet around town car, 617's don't need to be glowed as long and can be started up driven a mile and shut down. They don't seem to mind around town service, like the 603's do.

After have owned and worked on both for awhile personaly the SD isn't a bad car but if I were looking for another W126 I would prefer one with a 603.

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2006 CL500
2009 C300 4matic
1969 280SE
2023 Ram 1500
2007 Tiara 3200