I replaced a engine in a traverse due to a failed Thrust bearing in the bottom end. I scrapped the block but recondioned the heads. They have been milled and had a complete valve job done. Took off 0.008 to get them cleaned up. I did prewash them but you should wash them again for good measure prior to install. Came off a 09 block If I recall correctly. GM part numbers are 19329668 For the Right/Rear and 19329667 For left/Front