Hino is a division of Toyota, and builds commercial trucks and diesel engines for much of the rest of the world. Hino trucks are still sold in the US, so you might go to the dealer with the VIN of the truck you are looking at and ask about parts availability for older vehicles.
If I had to guess, I would say they are typical Toyota, stone cold reliable for hundreds of thousands of miles, thanks in part, to a very detuned engine, an overbuilt chassis and quite simple architecture on a truck that old.