Not to sound alarmist, but I just came from a garage where a 100k mile 2.5 turbo motor out of a '91 300D was sitting on a stand-all blown up. Turns out that this meticulously dealer-maintained car's vacuum pump somehow had some sort of spring break in it; that in turn jammed the timing chain, which in turn broke the camshaft, and on and on. Goodnight motor
The blown motor looked great from the outside, even had an almost-new injection pump bolted to it; appearances supported the "well-maintained" claims. If I hadn't already replaced both my vcacuum pump and injection pump, I'd be over there with a wrench set right NOW! Timing is everything, they say.
The crate motor from MBZ (cost $4,200 USD at wholesale) came with a new turbo, new injection pump, new vacuum pump, new alternator, new fuel rails & all clips, entire intake system etc. Absolutely complete. Really quite a deal if you're a big-mile driver