I was looking at my headers yesterday and found something ugly!! My head has about3-4in crack close to the valve cover kind of going around it? What would have caused this. I have no idea? Also mine are casting #862 and would some off a 2005, Casting # In the Head is 421 6P6984363 fit mine and whats the differance in them?
Also will thes heads fit ? LS6 heads part # 12564824

 

my cousin thinks its suppose to be like this and this is just where the valve covers come on just some info!

 

It's probably just casting flash and only looks like a crack...if it was really cracked it would be leaking something (depending on where the crack is). Never heard of a head cracking in the way you explained...can ya get a pic?

 

yea its not a crack but im get a picture for you!