I got this truck used with 80000. It had a bad intake gasket and got replaced. Engine has not given me any issues since. z71 4x4 is pretty dang nice, its hard to get this this thing stuck in the mud. Issue with the motor in the transfer case... but never stopped working (says service yada yada. been checked. not a big issue). basic maintenance and think I can give this vehicle to my kids (not soon either). GMC seems like a good truck with some quirks, but solid and runs when you need it. The 5.3 has some passing power, and tows like a champ. If you like your girls a little high maintenance, go on and get it. If not, then buy an old truck and forget about all the gadgets. good luck.
engine is solid.
Transfer case motor (read many people have this issue 300 bucks or so replacement)