He said Denali, which means AWD.
Honestly, this is what you need to do: tell the guy selling you are very interested, then take it to a mechanic for inspection. At that age/mileage, a lot could be wrong or about to go wrong. On the other hand, if it's been well-maintained and everything looks ok, that's a good deal. I bought mine with about 115,000 miles, but the guy who owned it was an OCD military guy with records for everything (he actually used OnStar to track his maintenance).
Make sure the air-ride is working and in good shape. That was the one thing that bit me after buying, and it's not cheap to replace those parts.