86-92 not only has more pep than the pre 1986 diesels, but they are quieter, smoother, more economical, more refined, and the list goes on. My personal favorites are the 1986-1987 300SDL and 1987 300D. The aluminum head issue usually gets blown WAY out of proportion - it's fairly easy to tell when a car has a potentially cracked head. If you don't have a cracked head, then don't let your car overheat - and you'll be fine.