Did we break our Avalanche? Do I need to get a 2500?

Cool, never heard of this problem with the 5.3 or 6.0. Sounds like owner neglect in the video of not changing the oil regularly. Regardless my previous version of the 6.0 had a lot of miles and sounded perfect. To the OP it's worth the try, u could get a 3/4 if u wanted it, but if your current truck pulls fine, this will buy u some time till you eventually find another truck that you like or keep the one u got.