I have an SDL and it hasn't given me any serious problems since the day I owned it. It had 225K miles on it, and I have driven it about 75K miles since. There is nothing wrong with buying an older MB. Just make sure the car has good records, a straight body, a clean interior, and it runs exceptionally well. My car exhibited all four of these traits, and that's why I bought it.

The 350SD had a brand new engine with modifed connecting rods put in it, with all the paperwork showing what MB did underhood. Even replaced the turbocharger! All that has happened with this car, so far with me, was a bad EGR valve. Had it with 190K, now have 260K miles.

The 300SE I bought was one of very few SE's I'd call peppy. It sounded strong, too. All books and records, back to the day it was first signed off. Body was straight as an arrow, and it only had 130K miles on it. No problems, but I haven't driven it that far either.

The 560SL recently had the chain replaced, so it shouldn't have any problems going 200K miles. I probably won't drive it for great distances, as this car is mostly garged. Same deal as the last cars, with all records stamped at the dealer. No problems, yet; too new.

The E420, doesn't really qualify as an old car, I think, but it came with complete books and records, too. Driver's side xenon headlight assembly went.$$ Ouch $$! @ 91K miles.

__________________
1987 300SDL (324000)

1986 Porsche 951 (944 Turbo) (166000)

1978 Porsche 924 (99000)

1996 Nissan Pathfinder R50 (201000)