Ive got a 2005 Navara Turbo Diesel D40, I think your right in thinking you only hear the bad stories and every car model will have one...
I was tossing up between the D22 & D40 at the time, both diesel, I preferred the 6 speed box and 2.5ltr engine for economy and also I think the power is up from the 3ltr, but then again alot of the 4x4 guys love the d22 for the down low torque of the 3ltr, as the 2.5 needs to be on boost to really get up and go, oh and it does. 1.85T is fun to drive around and yes you do feel like a truck driver compared to normal sedan drivers, and Ive never been a 4x4 or diesel driver, but now Im loving it... I regularly get 10.1 ltrs per 100Ks, I reckon thats good for the amount of weight Im haulin.
Things to look for, worn rotors, get one with a good service log book, look underneath for signs of a hard off road life
Keep in mind too that the canopies and hard tonneau covers wont fit that tray, so if you want a hard cover go the STR, I have the RX D40 and am looking for a STX tub so I can put a hard cover or canopy on it.
I towed a ute on a car trailer 4.5hrs south to drop it off I did the round trip (970Ks) on $135 of fuel, thats hauling 1.2T of car and trailer plus the 1.85T of 4x4 and it did it easily, 120Kph on freeway no problems, now Im planning to take it way out west for a desert holiday...
Just make sure the modification bug doesnt bite you, 4x4 and diesel upgrades are many... Im trying so hard to keep it standard
As a comparison I was looking at diesel STR D22s with 98,000 Ks 2004 for $19-$21K... thats in Sydney