A Disco is like any other Landy - you can mod it to your hearts content, so don't worry about getting one with/without leather - it can all bolt in later if needed. Condition is important. Mileage isn't too much of an issue, my Td5 is approaching 160k and still pulls like a train and runs very smoothly. Don't spend all your cash on the Disco - you WILL need to do repairs.
I can only mention Td5 specifics, but check for the following issues:
- fuel pressure regulator leaking
- oil in injection loom connector (red connector, on the ECU)
- leak from the fuel return pipe - chaffs on chassis near fuel tank
- steering box leaks
- PAS pump leaks/noises
- broken springs
- leaky dampers
- leaking ACE - pump, pipes, actuators
- leaking airbags if fitted
- leaking sunroofs
- nose from crankshaft pulley
- noisy turbo
- worn suspension bushes
- central door locking intermittent (locks need changing, no repair poss)
- worn ignition lock (engine can cut out without warning)
- poor c/locking remote range (receivers die if sunroof leaks water into them)
- rust on rear chassis - rear axle back
- rust at join of bulkhead and front inner wings (there is soundproofing foam on the bulkhead that holds debris causing holes)
- heated seat elements fail frequently (element breaks and can arc causing fire in seat foam)
- U/Js wear - need replacement every 100k along with rear prop donut
- check all electrics
- there should be no body rust - they just don't rust unless accident damaged
- roof rails readily corrode and lose paint
I think thats covers the main items, but there will be more lol. Check any prospective purchase over very carefully, and ideally take someone with a diagnostics unit to check the recorded fault codes.
Once sorted, the D2 is a great truck, worth the effort IMHO
HTH
edit - MPG wise, the V8s get 10-20mpg, the Td5 22-35.
edit 2 - forgot to add these. Spec sheets from brochures. First one is pre-facelift, second one post-facelift.