I just bout a 2002 Avalanche. I love it for what I paid for it, but I just discovered that the 4x4 is not working. Might be why I got such a good deal on it huh! Here is what has been done so far. I am in no way an expert so please be patient with me. Put it on the rack and pushed 4x4 hi button. Front drive shaft rotates, but wheels are not turning. Diagnosed as actuator, but it did not fix the issue. He now thinks that it has to be inside the drivetrain, and I am looking at least $1,500. I am not in any place to question a professional mechanic, and this guy is known as an honest one, but it seems to me that if there was a major issue that there would be some crazy sounds coming from that front end while that front drivetrain was rotating. Any and all advice and tips would be greatly appreciated.