This fitting is commonly used as a bypass port fitting on some of our 300 series pumps. WP300UP, WP301SP, WP311 and WP373 are examples of a few pump numbers where this fitting could be used. The #8AN end is o-ring boss configuration and the 5/8" barbed end is set to accept rubber hose secured by a hose clamp. The through hole is restricted so that less coolant bypasses the radiator.