Let me chime in on this one...
A few years ago, I bought a Shibaura SD 1843 4x4. From the looks of it, it was a nice machine. However, it was my first tractor purchase and it turned out to be a costly lesson learned.
Now this could happen to any used tractor but I'll explain just how expensive it was to have fixed.
I bought the machine for $6000 with a FEL and back blade just as the picture shows. I checked it over as well as I knew how and then took it home. When I got it home and ran it for a few days, I decided to change all the fluids and that is when I found out that the front end was bone dry (I was naive and didn't even know to check the front axle for fluid before I bought it). I filled it with the proper fluid and then discovered it had a leak. It cost me $1000 to have a seal replaced. After I got it home and was doing some backfilling (admittedly probably more then the machine was designed for) I snapped the front ring and pinion. It cost me $3000 to get that fixed. So now I was $10,000 into a $6,000 tractor. I had to get it fixed because I would have been out even more if I didn't. After it was fixed I sold it for $7,000 and cut my losses.
The parts were available but it took a lot of searching and trial and error. If I remember correctly, I had a parts manual but they were all Chinese part numbers with no cross reference numbers. The parts that were used were actually Ford parts. The SD 1843 is very similar to one of the Fords. However, the seal came from one Ford and the ring and pinion was from another Ford tractor so it wasn't as easy as finding the Ford tractor that was its equivalent and then assuming all the parts interchanged with each other.
I also found the place that originally imported and sold the tractor to the guy I bought it from was not all that knowledgeable about the tractor, and they sell "gray market" tractors a lot. I was pretty much on my own, except Adam's Tractor has a great service department and helped me out.
Again, I'm sure the SD 1843 was too small for my application and a leaky seal could happen to any tractor, especially an older one, but it was very expensive to fix.
I would suggest passing on it and looking for one that wasn't a "gray market" even though I'm sure it's tempting for the price and that it looks like a clean machine.
Just my opinion, good luck.
I attached a couple photos of the SD 1843 for a comparison.
Craig