I know of a local 1990 350SDL for sale, 95k miles. I called on the car and it seems real nice, the guy sounds as honest as you can be. Right off the bat he said it was burning oil and he and his mechanic can't figure it out. I didn't have the heart to tell him his engine was about to blow. He described classic symptoms of a rod bending.
Its a shame those W126's are real gems.
However if the car is real cherry and assuming the bottom end is shot it can be saved. He is asking $4400 for it and I bet if someone offered him $4k he would take it. Head over to your local MB dealer and order a 350 short block for $5k and for $9k you have a mint (95k mile) W126 diesel with basicaly a new engine. MB also includes a 4 year warranty on said short block.
If I wasn't so attached to my SDL I might jump on this one. As it is I am tempted to look.
If anyone is interested I would be willing to do a little leg work for them. I have the guys number. However don't waste my time on a passing interest.