I'm confused as to what the difference is between these two. I googled glasspack headers because my dad has them on his 69 Nova and they looked like a regular exhaust manifold. I looked under the Nova up to the engine and couldnt determine if I was seeing a manifold, or headers for the life of me. Also I just bought a 1980 Grand Prix LJ and was wondering how to find out if there are any aftermarket parts on the exhaust?