CBM Custom water neck fitting for most LS1, LS2, LS3 LS6, and LS7 style engines. This water neck is machined here in the USA from a solid piece of 6061-T6 aircraft grade billet aluminum. It presses in place of the factory steel push in piece accepts a -20AN fitting. Simply pull out the factory 1.5" barbed fitting and press or weld this unit in place. This auction is for 1 top press in fitting in a -20AN short style (bottom bolt on fitting is available separately). The press in fitting is available in a long version as well as -20AN and -12AN sizes. This fitting has a 1.299" base. It will only fit Genuine GM pumps and may be too loose for aftermarket pumps. For aftermarket pumps, we recommend running our CBM-10621 top fitting with a 1.310" base. It will also work with many of the 4.8L, 5.3L, or 6.0L truck water pumps. Please verify your original fittings size before placing your order. We are not responsible if the fitting does not fit your pump.