Those chevy 6.0s are a joke! The oil pump and oil pump pickup O-ring are both junk and frequently destroy engines. Also the cam bearing likes to spin in the block and you have to pull the engine to replace them as some of them only come in through the back of the block. I can't for the life of me figure out why the 6.0 has these problems while the 5.3 is built the same way and doesn't have the same problems but we replace about 10X as many 6.0s as 5.3s and finding a good used 6.0 is a lot more money than a good used 5.3, it usually saves $1000-$2000 to swap in a much more reliable 5.3 and so far every customer has said they can't even tell the difference in power but MPG is significantly better. Also unlike the Hemi MDS system those newer LS engines with their version of MDS are horrible.