We now have the water fitting that mounts in the cylinder head, GM # 499744 . It was discontinued from GM in October ‘07. The original GM number was 9781091 which GM superceded in the early 70s. That design had a spring on the inside to restrict water flow. GM had failures with the spring style and the changed it to a rubber restrictor, which is more forgiving in all temperature conditions. Fits 1965-81 Pontiac GTO / Judge / LeMans / Tempest / Grand Prix / Firebird / Trans Am models with 326 389 400 428 455 engines.
