GM Hairpin Alternator 05-13



The J2Fab 6 phase hairpin alternator is our premium offering.  Rated at 300A(Small Case) and 370A(Large Case) these 6phase units offer greater idle performance with a higher efficiency than other units available for your GM Truck or Car.


  • 100% new components and direct bolt in case.
  • Custom rotor/stator to decrease air gap to improve idle output.
  • Balanced rotor and 0 run-out slip rings to improve unit life and eliminate battery light flicker.
  • Heavy duty 12 diode twin rectifier plates
  • Improved air flow to ensure long service life in severe conditions
  • NTN premium and NSK USA bearings.


Overdrive pulley options available and only recommended for non-performance oriented vehicle applications.  Best suited for car audio builds.

If you select custom powdercoat colors – please remember to add your desired color into your order comments

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Additional information

Additional information

Weight 15 lbs
Dimensions 12 × 12 × 12 in

300A Small Case, 370A Large Case


Matte Black, Wrinkle Black, Custom, None

OverDrive Pulley

Yes, No

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Refund Policy
Due to the custom and many times built to order nature of J2Fabrication products we have an all sales final policy. Standard lead times unless otherwise specified on the product page or in discussion is 4wks. Any refund request granted is on a case by case basis at the discretion of J2Fab and may be subject to a 25% restocking fee. Orders cancelled before shipment are subject to a 15% cancellation fee. If you are looking to return a product for warranty work or maintenance, please email [email protected] with “RMA Request” in the subject line.