I just recently purchased my first MB. I bought an '86 300 SDL. I am so in love with this car!!! I have heard from a few people that the 603 engine was not very reliable and that was why they didn't put it in production for very long. Since I'm a newbie, I'm not sure whether this was bogus info. I am hoping this is the case. What can you tell me? I am also planning on doing a vegetable oil(SVO/WVO) conversion on the engine provided that I can find someone to trust to do the work! I am not an experienced mechanic and I would prefer to have a little more experience with diesel engines before I try to tackle something of this magnitude.