I've got a triton now for work, its entirely adequate in every way except the power curve. that thing has the worst turbo lag / soft take off i've ever experienced, which isn't great considering its a diesel. once its past 2000rpm its all good, but below that it feels like its being powered by a rubber band engine. My experience might be different to others though, because with my bare minumim of tools and equipment, the car weighs in at 2.7ton at the tip. throw a trailer on that or a couple of hundred kilos of scrap or rubbish and you can imagine why I gripe about it.
I had the old 3.0 diesel D22 nav before that, the odo got to 560,000 before i sold it on, and ive been told it continues to tick along just fine too. it had nowhere near the top end power of the triton, but was reliable and easy to work on and didn't have to wind up the rubber bands to get some power on take off. Being a nav owner for a few years i got to know the forums for those things and i doubt i'd buy a 2.5 diesel nav. apparently they had an issue with stretchy timing chains on some builds which would let go anywhere from 80,000km upwards and more or less destruct the engine. they used this engine in the D22 and D40 so you're probably not safe either way.
...whats the deal with your D22? is brokened?