My JTD has 133,000 miles now.
From what I've discovered of it's life history (poking around, in and under it);
Exhaust will rust every 65,000 miles or 5 years... My beast is just on its third silencer (fitted by me).
Suspension - unknown history viz. front wishbone arms but the dampers and springs on my old beast are factory originals. No problems with front tyre wear so I presume the wishbone arms were changed at some point (that or they last 133,000 miles, which would be epic).
One (original) rear bush was squeaking on mine (lost fluid) so I swapped the pair. It's aboot a £150 job, including bushes.
Brakes... my discs are at least the second set it's ever had... but they're lasting okay, so I doubt they are the third set. Pads.. probably been swapped more often.. but let's see.
The body looks pretty 'ard. Not much corrosion (odd spots on the underside) and it appears difficult to dent (although a few people have tried).
Clutch lasts 120,000.
Tyres last okay .. . If you swapped front and back to spread the wear, I think they'd go to 30,000 miles.
EGR valve can soot up. It can soot up even more if you overfill the oil (the crankcase breather vents excess oil/mist into the inlet manifold).
The MAP sensor can get bunged up with oil.. (see above).
MAF sensor lasts 130,000 miles and a new one (original Bosch) will pay for itself in no time with extra mpg's.
Lambda sensors - mine is on it's second one. Use the original manufacturer (Bosch) with a moulded connector block, not a cheapo un-named brand which you have to splice in.
Instrument console can play up. It's all CANBUS and computerized with a lot of stepper motors. It's not tooooo severe to fix (Yellowstilo - a member on here can do them cheaper than a Googled specialiste). I bought a spare set (mine got lost in the post) and they packed up shortly afterwards, so it's a fairly common problem.
On mine I had problems with the Body Control Module which seem unusual on the Forum. That's all CANBUS and holds the immobilisor codes so you can't just throw it away and fit a new one. I needed to find someone who could transplant the EPROMS from my old one to a second-hand new one. No problems since.
I have an intermittent problem with the Central Locking to the rear passenger door (5 doors).
The mirror demisters don't work.
The Air conditioning compressor seems FUBAR.
I don't know that these few issues wouldn't affect any other 13 year old car .. My biggest aggro' has been the electrical issues (BCM and console) since they affected me being able to use the car (MOT) but otherwise it's been pretty much "okay"... other than to sort the inherited problems and the instrument console failure, I've only needed to fix the clutch, the silencer and fit new pads. I can't really grumble.
Ralf S.