Those model suburbans are beasts. we had a 97 same drivetrain and it went 300K. The AC in them is famous for leaking refrigerant at the rear condenser that is behind the right rear wheel in the hump that extends inside to the rear door. If that is it it is a simple fix. Pressure test it beofre you buy parts and coolant since the AC system holds 4 lbs of 134a.It needs a good shampooing, but I agree it's in great shape. When I went to look at it I figured it would be a rust bucket, but was pleasantly surprised.
I posted it online for $3400 and have several people that want to see it. At $2600 it is a steal. I'm basically giving away 10 hours of my time and most of the risk, but like I said I have other vehicles in Georgia that can accomplish the same thing.
Only unknowns are AC, but it could be as simple as a top off and o-rings. Even if it's a compressor they are cheap on these ($130 on rockauto for a cheap version). I just drove it all morning and the oil hasn't even left a drop on the ground so it must be pretty minor; when I got it, it was leaking like crazy from the oil cooler pipes.... it was a total mess, but all done now.
My plan was to drive it as is for the winter to make sure I didn't find any other surprises, then if all was well mess with the AC later in the Spring.