Td5 manual disco just has em die. Not had to do one on a defender but they normally don't do as near the Kms as discos due to people not using em much for high driving so that probably why.
Too much movement between the "halves" so it causes bad running and crank sensor DTCs. You can get a non dual mass ive been led to believe so you will never ever have the problem again but don't think it's a genuine LR part as never fitted one in dealer only replacement ones.

The injectors basically cock up and die after high kms. If the cars running is rough/underpowered/high fuel consumption you view the individual injector compensation using real time display on either t4 or autologic. if its out of tolerance slap a new injector in the one that's causing issues, recode it to the ecu (very important to do so -wont run well if you don't) and that's the job done. BUT can be tricky to get em out as if the injector seal (copper washer) has been leaking as a massive carbon deposit builds up, then they a stubborn bugger to get out! Same goes for the freelander 1 td4 engine.
If you have a stubborn one, pour coca cola on it and leave it overnight, sounds weird but it works! Been a long long time since I've done one though as they don't come into dealers very often any more.....well they didn't in the uk but seeing more of them now I'm in OZ but only been back with landrover a month as I've been working on 4x4 cars.....ahhh the beautiful cosworths