Alternator 120 AMP 12V 4" Dual Foot Saddle Dual Pulley with Isolated GroundAlternator, 604 Series, 120A, 12V, Saddle Mount (Dual Foot), 4in, Deep Dual Vee Pulley, Isolated Ground 4" J-180-Style Mounting;  Typical for Caterpillar, Cummins, Detroit Diesel & John Deere EnginesReplaces: 604-120-SR-IGThis product may not be returned to the original point of purchase. Please contact the manufacturer directly with any issues or concerns. This 12 volt alternator has dual mounting feet and a 120 Amp output and is fitted with a pulley for a dual V-Belts High output 12 volt 120 amp alternator fitted with a dual V pulley. Small case, isolated ground. Yanmar style dual foot mount Externally regulated single output. Patented SmartReady backup internal regulator. Certified ignition protected for gasoline or diesel motors. High volume cooler running dual internal fans This alternator comes with a pulley for dual V-belts Datasheet, dimensions, output curves Tech Tip When you mount the alternator to the engine the mounting bolt must be the same diameter as all the holes it passes through. If it isn't bushings are available to modify the mounting tabs of the alternator. When you tighten up the mounting bolt the bushing at the back foot of the alternator slides forward to tighten up the gap. At this stage the alternator should be firmly fixed with no wobble. You must get this right or the alternator will become cocked as you tighten up the belt and the resulting misalignment will cause excessive belt wear.