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Holley EFI

Unterminated 15' Flying Lead Main Harness

Pre-Terminated J1A / J1B 15' Flying Lead Main Harness

Part # 558-126 Be the first to write a review
Estimated shipping date: 10/25/2021
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The unterminated main harness comes with both J1A and J1B connectors full terminated with 15' of flying lead wiring.


  • 15’ long flying lead harness, allows you to completely customize your main harness installation
  • 60 Holley Crimped Wires (57x 20 ga, 3x 18 ga)
  • 30 optional plug seals

About Holley EFI

Holley is the new standard in EFI! Whether you're engine swapping your classic car or need to manage 4000 horsepower in your twin-turbocharged drag radial race car, Holley EFI has the solutions you need to get your project up and running better than ever!

Brand Holley EFI
Emission Code4
Harness ApplicationUniversal
Harness TypeMain
Product TypeUniversal Unterminated Main Engine Harness
Part Number558-126

This part is legal for sale or use on Racing Use Only Vehicles

The following vehicles are considered Racing Use Only Vehicles:

  • Racing Use Only Vehicles are vehicles that are used exclusively for competition that are not registered and that may never be used on the street

WARNING: It is against the law to install this part on an Emissions Controlled Vehicle


    *Free Shipping & Handling only offered to the contiguous US on orders over $100, excludes clearance parts and oversized packages.

    Some parts are not legal for use in California or other states with similar regulations.