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    Eaton Detroit Truetrac Helical Limited-Slip Differential | Ford 9in 28-Spline, 9in Ring Gear | 912A587

    Vendor: Eaton
    Part Number: 912A587
    Regular Price $685.99

    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 Eaton Detroit Truetrac is a helical gear-driven limited-slip differential that maximizes available traction while sharpening handling and drivability. It works smoothly and automatically, needs no maintenance, and avoids the on/off behavior of a locker, which makes it a strong choice for street, tow, and trail use.

    • Type: Helical gear limited-slip differential
    • Axle: Ford 9in
    • Ring gear: 9in
    • Axle shaft diameter: 1.20in
    • Spline count: 28
    • Gear ratio: 3.25 and up
    • Part number: 912A587

    Axle Fitment

    Fits the Ford 9in axle, 28-spline, 1.20in axle shaft diameter, with 3.25 and numerically higher ratios. This axle appears across 1957-1980 Ford applications and many 9in swaps. Confirm your axle and spline count.

    FAQ

    What axle does the Truetrac 912A587 fit?

    It fits the classic Ford 9in axle with a 28-spline count and 1.20in axle shafts, using 3.25 and numerically higher gear ratios.

    Will it work in a Ford 9in swap?

    It fits the Ford 9in axle by spline count and ratio range. Confirm your carrier bearing size and 28-spline shafts before ordering.

    Does the Truetrac need maintenance?

    No. It is a helical limited-slip that operates automatically and smoothly with no maintenance and no locker on/off behavior.

    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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