I currently own a 1990 420sel but I've always loved the turbo diesel Mercedes(the sound is what got me). I would like to either buy a 300sdl or 350sdl. I've heard of the head warpage on on 350s and connecting rods bending. But I think I've heard certain 350sdl engines were ok depending on the number on the head or engine or something like that. Could someone just inform me a little more on what the pros and cons are of each or what to look out for and possibly which years were the best. Just stuff like that. Thank you all.