Race Pro Radiators - 30 3/4 x 19 1/2 x 3 1/8 GM Triple Pass Machined billet aluminum SAE compliant filler neck; Triple pass radiators pass coolant through the radiator 3 times before exiting and require greater flow than standard radiators; it is recommended that you use 1 to 1 pulleys, a high volume water pump, and use no restrictors in the system;