The quality on the new 5.3's is very good. My dad has well over 100k on his with no power loss, no oil consumption, runs very quiet, etc... The only thing that failed on the engine was a piece of smog equiptment, but that stuff always fails on all engines. I feel that the reliability of cars has fallen off significantly because of smog control equiptment. The major problem with the new GM's is the 4l60 transmission. It is pretty much a 700r4, which was designed to work with the 160 hp 350's of the early 80's. Now, it's behind an engine that makes 285 hp which makes a large percentage of its peak torque from 1000 rpm.