I wouldn't be afraid of one because I wouldn't own one. Too many fiddly vacuum bits for the emissions controls, 350SDL specific driveshaft and engine mounts (which are very expensive), an ASD system that's a "meh" afterthought to adding traction control, and of course an engine that has weak connecting rods and an appetite for head gaskets. There are people out there that love them, but if you're not in the market for some potentially expensive repairs with hard-to-obtain parts, look for a 300SDL if you're wanting the LWB 126, or consider building a 3.0L 603 or 606 to go in there.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]