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    Sale!

    Holley EFI Gen V LT Engine Main Harness, For Terminator X/X Max | 558-129

    Vendor: Holley EFI
    Part Number: 558-129
    Save $77
    Sale Price $611.95 Regular Price $688.95

    Available to order. In-stock orders typically ship in 1 to 2 business days.

    Not sure it fits your vehicle?
    Email sales@berryperformancesales.com with your year, make, model and engine, and we'll help you check fitment before you order.
    Fast Fulfillment: In-stock orders typically ship within 1 to 2 business days.
    Free Shipping on Orders Over $99 | Excludes freight shipments
    International Shipping Available: email sales@berryperformancesales.com for a quote.
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    This Holley EFI Gen V LT engine main harness is designed exclusively for use with Terminator X and Terminator X Max ECUs on GM Gen V LT engines, with wires routed in protective loom.

    Specifications:

    • Engine: GM Gen V LT
    • Crank Reluctor: 58x
    • Harness Type: Main engine harness
    • Compatible ECUs: Terminator X and Terminator X Max only
    • Construction: Wires routed in protective loom
    • Part Number: 558-129

    Compliance: This part is legal for sale and use on Racing Use Only Vehicles — competition vehicles that are not registered and never operated on the street. It is against the law to install this part on an Emissions Controlled Vehicle (1966-and-newer California-certified or 1968-and-newer federally certified vehicles).

    FAQ

    What ECUs is the 558-129 harness compatible with?

    Terminator X and Terminator X Max ECUs only.

    What engine platform is this harness for?

    GM Gen V LT engines with a 58x crank reluctor wheel.

    Are the wires protected?

    Yes, all wires are routed in protective loom.

    Shipping Policy
    • Free shipping on orders over $99 (excludes freight shipments).
    • In-stock orders typically ship within 1 to 2 business days. Weekend and holiday orders are processed the next business day.
    • Orders ship from Defiance, Ohio and a nationwide network of warehouses and manufacturers.
    • Items showing an ETA are not in stock yet. ETAs come from the manufacturer and can change.
    • No P.O. Boxes. International orders need a shipping quote, so email us first.

    Read the full Shipping Policy

    Return Policy
    • 30-day return window from the ship date. Returns must be approved first; email sales@berryperformancesales.com with your order number.
    • Items must be unused, complete and in the original packaging.
    • A 20% restocking fee applies, and return shipping is paid by the buyer.
    • Not returnable: installed or modified parts, opened or used programmers and tuners, custom orders, Open Box, and Clearance or Final Sale items.
    • Damaged, defective or incorrect items must be reported within 48 hours of delivery with photos.

    Read the full Return Policy

    Disclaimer

    All products are sold for off-road use only unless otherwise specified. Buyer assumes all responsibility for installation and operation. Seller is not liable for any incidental, indirect, or consequential damages — including engine failure, labor costs, or vehicle downtime — resulting from the use of any product sold.

    By making a purchase from Berry Performance Sales, you acknowledge and agree to abide by the terms and conditions of these Policies.

    For any questions or concerns, please contact us — we’re always happy to help.

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