I'd have to say that the strangest production diesel engines in my lifetime were easily the GM conversion engines. They get an A for innovation and an A for getting it done on a very short time schedule.
They get an F for actually making an engine that could get the job at hand completed with any sort of class whatsoever. My uncle's old diesel (I can't even remember what model it was, if memory serves, they had two models of gas to diesel conversions. I'm sure someone will correct me if I'm wrong, but it was the 5.7 V-8 and the 4.3 V-6) could NOT drive up my Dad's driveway. He had the throttle floored, in first gear, and the car just sat there with the tranny slipping, not having enough power to get it done. Granted, my Dad's driveway was steep, but to not be able to make it up even the steepest of driveways is pretty bad. We had to tow him to the top.
Of course, there was the problem with them breaking, too. Apparently, 350's weren't designed to run 22 to 1 compression ratios without breaking a lot.
It is a crying shame that it didn't work, because I really think that it would have opened the door to diesels in america if those rigs had actually performed like their gasser counterparts, and still got 30% better fuel economy. I think that you would have seen every other manufacturer follow suit with similar conversion engines, and a whole new industry of cheap, light, easy to manufacture diesel engines would have come out of it. Too darn bad.
