My 1500 NA now has 170K on it, I feed the beast roughly 20-30% home brew bioD. Gets 17-20MPG, easy starts and no smoke after start. Leave it alone or change out the injectors and glow plugs before winter?
I actually got ahold of the mechanic at VDOT. He said unless it's broke they didn't change the injectors. what the did do was change the oil every 5k and poured in a bottle of injector cleaner. hell, if everybody with a Diesel vehicle did that we'd see a lot more old oil burners on the road.
I would pull the injectors and have them tested for pattern and pressures. A perfect DIY. It will start to have a bad spray pattern before you have any problems. Then if you have that pop tester in the future and it starts acting silly you can diagnose it pretty quick.
I know 100k is the magic answer, but we ran them in the fleet for over 200k with a high success rate- around 70% iirc. Many engines went away with cracked blocks but good injectors at 225-250k.