Problem w/ High Lock?

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I had this exact problem with my 03 Avalanche when it first happened i never thought anything of it but then it kept doing it as i was driving it would do it and it kept getting worse and it was shifting on its own and terrible noises got it in and cost me about 1200 was the transfer case thank god they say they have the problem fixed in the newer vehicles have not had any trouble with my 07 sut