yer?
the diff's start making lots of noise but they dont break easily, just whine louder and louder.
gearbox all depends on how you drive, can kill it 100kw if your an idiot, but probably a good idea to get a 33 turbo box, 34 is pull type clutch which makes it harder
as for the tailshaft with a 25 box, easiest way is to get a shop to put a vlt/33 yoke on your standard tailshaft, or if you wanna spend a bit more get a custom single piece made up