Cylinder lines? I have no idea about what you are talking about. There may be fuel injector o-rings but I’ve never heard of cylinder lines.
Just a guess but I suspect they have round O-rings.
“(C)ylinder lines”??? OK, I give up! What are cylinder lines? I’ve heard of cylinder liners, more commonly referred to as cylinder sleeves. I guess you call a line cylindrical but that is just redundant…
What cylinders are you talking about and what kind of lines?
I’m going to eat dinner

what kind of o-ring does the cylinder lines have on a 2006 gmc envoy?