Having owned & driven several Mercedes (mainly Diesel), I must say that this one (1991 350SDL) is among the greatest, if not the best version, in my opinion. One thing I must state first off, is that I am a retired Long Haul Trucker, and have been most of my life. Having said that, it should be obvious that I would tend to gravitate to a QUALITY Diesel equipped vehicle, as the engine itself is one that is, by it's nature & design requirements, built to extreme durability standards. Other manufacturers have attempted to "go diesel" and have failed miserably. Mercedes has been in the diesel engine building program for themselves almost since the diesel engine was invented. Because a quality built diesel engine is built so strong, they typically run 500,000 miles, or more, before needing any great investment in a re-build, etc. Even then, most Truckers will do what is known as a "top end kit" to refresh the cylinder liners & pistons at 500k miles & "Keep on Truckin'. There have been statements presented (here & on other "info sources") that THIS engine is "prone to connecting rod and/or cylinder head issues/failures". THIS IS AN INCORRECT STATEMENT FOR THE FOLLOWING REASONS - At the same time that the 350 diesel engine was introduced (to replace/upgrade from the 300 diesel engine), the U.S. changed their diesel fuel "structure" so that it produced a vastly different fuel than had been historically been available. This was done to appease the EPA & the environmental community. This change was NOT publicly "advertised", so no one knew what changes it would make to ANY diesel engine. This resulted in damaging MANY diesel engines across the board here in the U.S., and subsequently the EPA had to actually formulate the "fuel chemistry" so that it would no longer be harmful. Of course, this "news" was not available until way after the fact so that EPA would not be sued for the damage done due to their lack of proper formulation within the realm of the power characteristics within a diesel powerplant. Thus the birth of the theory of blaming the engine manufacturer, instead of the True Culprit - EPA. It truly bothers me everytime I read statements blaming engine manufacturers for something they had no knowledge of or power over, here in the U.S. Currently my 350 SDL has 174,000 miles on it, has been maintained according to the factory guidelines, and at a recent "physical" I had conducted for my own "peace of mind" - my mechanic states that it is running SUPERB. The shop I use is one that highly esteemed both here and throughout the Mercedes Community nationwide. Matter of fact, the Mercedes Club of America is where I found out about them in the first place when I moved here. NOTE: PLEASE don't think that I'm some sort of "hi-roller" because I seek advice & mechanical advice from such a notable organization - quite the contrary, I assure you. However, I DO believe in seeking advice from the best possible sources - it just makes common sense to me, as I want my dollars to stretch as far as possible, while enjoying an extremely well built car as Mercedes! My main point is this - that the Mercedes 350 Diesel engine is EXTREMELY RELIABLE. It's 26 years old and it runs as good or better than new cars that I have driven. DO YOUR RESEARCH ON THE VEHICLE AND IT'S MAINTENANCE HISTORY - LOOK OVER THE VEHICLE IN DETAIL, AND MOVE FORWARD ON THE PURCHASE OF IT, IF IT "SPESAKS WELL OF ITSELF" TO YOU!