Disco 2's rear chassis rots if not watched out for/checked/repaired etc. The TD5 178k miles should be no issue if it's been regularly serviced. You can get about 27mpg - less thirsty than the V8 (still sounds good, but never as good as a V8
)
Road tax for the TD5 is £280 -
the V8 is more I believe.
I "think" most of the cracked head issues were gone by 2001 and onwards..... I "think"....hope... cry etc. (Mine's 2001 XS with almost 160k on her)
Disco 2 wheel bearings = the entire hub including the ABS sensor wire. Budget for £60 upwards a corner V8 or TD5 no matter. Any play in the wheel hubs = replacement.
Do a search for the three amigos - there should be none of those lights looking at you if and when you test drive one.
ACE system (Active Cornering Enhancement) - some parts are pricey. Does get bypassed by owners fitting a kit or part of a kit to remove the ACE capability (mine was bypassed before I bought her). As does the SLS - the rear airbag suspension sometimes gets converted to coils (mine was!)
Sunroofs can and do leak, but this is equally possible in Disco 1s
Have a surf around the Discovery section to see what problems there might be