Alternator for Chevy, GMC, & Isuzu Medium & Heavy Duty Truck 3.9L 4BD1/4BD2 with Vacuum Pump Included 12 Volts, 70 Amps 12 Volts, 70 Amps Output Stud Dimensions M5-0.80 Vacuum Pump Included! Regulator Position at 9:30 One year warranty