RAD Industries 2JZ-GE Billet Upper Water NeckRAD Industries 2JZ GE Billet Upper Water Neck This RAD Industries Billet Upper Water Neck is for the 2JZ GE head and will allow you to adapt to AN fittings on your GE engine. It has 16 ORB female threads so you can use a union fitting for either 16 or 20 for your upper radiator hose. The upper water neck uses an o ring to seal to the head so no gaskets are needed. It has two ports on the bottom, a 1 8" npt and a 1 4" npt for a sensor or for coolant