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    Sale!

    Holley Pro Dash M8 Service Harness, For 6.86" and 12.3" M8 Pro Dashes | 558-486

    Vendor: Holley EFI
    Part Number: 558-486
    Save $18
    Sale Price $142.95 Regular Price $160.95

    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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    The 558-486 is Holley's factory service harness for 6.86" and 12.3" M8 Pro Dash displays, giving you a direct replacement connection using the same single M8 connector as the original harness.

    Specifications:

    • Product Type: Gauge Wiring Harness
    • Compatible Dashes: 6.86" and 12.3" M8 Pro Dash
    • Connectors: (1) M8 connector
    • Finish: Black
    • Part Number: 558-486

    Verify which M8 dash version you have before ordering, since connector revisions can differ between dash generations.

    FAQ

    What does the 558-486 harness fit?

    It's a service replacement harness for Holley's 6.86" and 12.3" M8 Pro Dash products.

    How many connectors are included?

    One M8 connector, matching the factory harness configuration.

    Should I check anything before I order this harness?

    Yes — confirm your M8 dash version before ordering, as connector revisions can vary.

    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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