It is past the 25 year mark, so it can be registered in the US. I too would probably jump on that if I were in your shoes. I do see some oil leakage near the drive shaft in that image you posted, so that's clearly one area to dive into post-purchase. Also unless the current owners have done the regular maintenance, I'd probably go through and replace most of anything rubber in the engine bay (belts, hoses, etc.) I'd switch to stainless brake lines if they're not there already, replace those shocks, clean the engine and undercarriage to check for any other leaks, and probably redo the wheel bearings/repack hubs if they haven't been done recently. That's a fair bit of work unless you do it yourself, but that would get you a reliable Troopy that would go for another long while.
Yeah , that sounds like a great to do list.
It appears that the excessive oil leak is likely do to the seal between trans and transfer case. It looks like at one point it has one of the aftermarket bypass hoses that sends fluid from trans to transfer case so transfer case is fuller and seeping out of the o ring at top of transfer case. From what I could tell and what one of my mechanic buddies told me quickly... if anyone knows what I am taking about, let me know (I think specter sells them but don't even know what it's called). It looks worse than it actually is from the photo.
Also, clutch assembly was replaced and most rubber/bushings were replaced before they took the rig across the world some 30k km's ago.
Some other known Issues:
1. He did mention that some o ring gave up the ghost in the injector assembly that was replaced.
2. the water pump was fixed temporarily in mex but he wants to replace it,
3. It could use a new timing belt.
4. The tach needle isn't operating - he mentioned a loose wire.
5. Has AC but isn't hooked up at the moment. Not sure if I have to convert it.
It cruises fine on the highway and was actually surprised it would go 65 fairly easily.

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I don't notice any alarming whining from trans or transfer case, but to be honest it's the first one I have ever driven so who knows...
Almost too much information but thankful to know some of the history and it's known issues.
Thanks for all the advice thus far.
Cheers.