IIrc when GM went to the new 900 series that had the cylinder cutoff and forgot to shutoff the injectors to those cutoff cylinders, cylinder walls and oil were getting washed out with gas and ruining the engine usually right about the 50k mileage. Now they're going with the moronic engine stop-start crap at every stop. At least you can shut it off for now but have to do so every time you first start it up.I bought and 00 and a 05 both new new. Sold the 00 with 242k miles and going strong but rusty. Only thing I did to it was a fuel pump, alternator, and front wheel bearings. 5.3 is a great motor. No oil leaks and rarely add oil between oil changes with my currrent high mile truck. Still have the 05 guessing in the 240k range. Its rusting but no oil drips and I add about a half quart of oil between oil changes at 4k. Paid cash for it and plan to keep for a couple more years. One of my long time renters is a GM mechanic he tells me the 5.3 had some really bad problems when they first came out with cylinder shut down. Not sure of the years but he said he lack of oiling and on a weekly basis were rebuilding motors or mostly piston replacement. Good luck with your tuck. Its nice looking ride.
GM ceo mary barra idiot should be run out of town on a rail before the whole company is chinese owned.