Okay, latest thing learned, valve stem seals for double valve springs on a late model head. The late model heads have the valve spring seat and seal as a one piece assembly and will not work with double valve springs. What you have to do is replace them with the seals from the earlier 98ish LS1 heads. The FelPro part number for the seals is SS70945 and comes with 8 intake and 8 exhaust seals, seperately bagged with a guide you slip over the valve stem to protect the seal during installation. I used a deep 13mm 6 point socket and extension as a driver to install the seals.