-Previous owner broke (only) key in ignition
-Previous owner replaced ignition switch => 1 new key
of course this "new" key doesn't fit the tailgate, lock boxes or spare tire lock:
Went to local Chevy dealer, they looked up the VIN, made me a key
Great news it works in tailgate and lock boxes., bad news the door and tire lock won't rotate. I suspect since it has electric door locks neither of these got operated frequently enough and 17 years of "up North" winters and salt froze 'em up..
near term action: WD40 the snot out of 'em & see if that frees 'em up over time
long term action If that doesn't work I guess I'm replacing the drivers lock cylinder
Each time I change the oil (on my "normal truck") I lower the spare tire to "exercise" the mechanism.. I've owned this 17YO Avalanche less than a month.. I've got a bad feeling this has not been done in quite a while (I.e. the lock is seized).