I have not seen the records yet but what are the chances with the miles that the heads were done and shafts rebuilt. This would be my second Disco sold a 97 Disco a few years back This one is a good price

 

From every I have read, chances are both failures would have happened by now.
Price is key.

 

Under $3000.00

 

Shafts even if rebuilt can have problems if not greased on some kind of schedule, every oil change is good. If you can, pay a pro to eyeball the truck for general things, like slipped sleeve making noise, running hot on a scanner (won't see it until too late on the gauge), warning lights not functioning, etc.

 

I have a scanner that reads temperature I was planning on checking, it might also need O2 sensors. I was going to check the shafts how can you tell if there are rebuilt.

 

I looked at the truck it has an oil leak to the back higher up from the valve cover on the passenger side. Any ideas what is leaking oil in this area.

 

There is nothing that can leak oil that is higher the the valve covers.
As for the other things mentioned, do you have fault codes to verify what you think needs to be replaced. The drive shaft, as already mentioned still needs to be inspected and make sure there is 1 grease fitting on each of the 3 front u-joints.

 

Where the pcv hose enters the valve cover or manifold could be blocked up. Mine was. This could be causing it to leak on top of the cover?

 

Check # of grease fittings. Should have 3-4 for a rebuilt...1 if it's stock.