My 09 Tahoe LTZ dash has not cracked, but I may know why. I'm the second owner, at some point the first owner had the dash apart. The clip in the middle of the dash, by the center speaker, broke off (it clips to the smaller part of the dash for the defroster vents. So since that part of the wasn't clipped, the 2 parts move separately. I added a foam block under the broken clip just forward of the center speaker, because it just flexed up and down so bad. I've had it like this for well over a year and so far, no cracks. I believe the clips that hold the smaller part to the large part of the dash is what causes the cracks to start in the first place, because that small part doesn't flex much because it's small, and it pushes down on the large, mostly unsupported parts of the dash, and it just flops up and down and wears out like a credit card does when you fold and flex them. This is just a theory of mine.