I bought this kit to replace a 3v 5.4 headset. Since the truck is 12 years old and has 107,000 miles, I had no intention of reusing the originals. All the gaskets in the kit came and fitted perfectly. I did not use the small o-ring that comes with the kit. I think it's the crankshaft sensor which I left in the timing case. You will need an oil resistant RTV for the connection points where these gaskets meet the cylinder heads and oil pan. Just like the gaskets and engine were designed, the RTV fills the very small gap left in these seams.