I have a 2002 Avalanche with the 5.3 small block. It looks like I might have a set of those Castech heads that have a history of cracking. I was told on the Avy forum that LS1 heads will work on these engines. The question I have is that I have seen some with 806 casting numbers and some with 853. What is the difference? Which set is better? Anybody on here close to Seattle that has a set they want to get rid of cheap?

 

I believe they are the same cc wise at 66cc but the 806 are perimeter bolt and the 853 are center bolt.

 

Thanks.