also,before Ford came along the 6.9 was a spark plug engine.A very over built spark plug engine!But everything ford has had in the past is a turned up IHC bus/straight truck engine.That is one of the main reasons the sick point Slow is a total failure.IHC built a good engine that did its job but ford said they wanted it for their trucks but they wanted it turned up to the max,High RPM(which NO medium to large diesel is designed for),and some experimental crap to get around pattents.Intermational/Navistar hasn't had near the failures of the 6.0 that ford has.Basically the same for the IDI without the major failures.Ford wanted a diesel back in the early 80s and for some odd reason they went the same way as GM and converted a gasser to a diesel but with success.Slap some diesel heads on it,new pistons,and away they went.