As with any used car, this one is only as good as the maintenance it has received from previous owners. The price seems about right for a 2000 4x4 Yukon, and if it was treated properly and maintained according to the manufacturer's suggested maintenance program, the truck may be good for thousands of trouble-free miles... Or the engine or trans could explode tomorrow. You never can tell with used cars.
Personally, I don't think I would spend that much money on a 10-year old used car with that many miles showing on the odometer.
well there is no way to say how much good service you will get before a major repair will come your way. But with that said the Chevy Suburbans/Tahoes and GMC Yukons are very good trucks. I have seen them with many miles on them and be just fine, but it depends on previous onwers and maintanance they did.