USA Standard Gear

31 Spline Ford 9-Inch Differential Spool

$179.89

SKU: ZP FSF9-31

In Stock
In Stock
Ships by Aug 31
Free Shipping over $200
$100 Minimum Order
30 Days Return

Description

The USA Standard Gear spool (ZP FSF9-31) is engineered for Ford 9-inch axles featuring 31-spline configurations. This component provides a robust solution for achieving 100% traction to both wheels simultaneously, directly replacing the factory differential carrier assembly. Constructed from premium 8620 steel and subjected to heat treatment, the spool is built for enhanced durability and strength. This differential spool is specifically recommended for dedicated off-road and drag racing applications, where its 100% lockup capability offers a significant performance advantage. The USA Standard Gear spool fits a wide array of Ford, Lincoln, and Mercury vehicles, primarily from the 1950s through the 1980s, including models such as the Bronco, E-Series vans, F-Series trucks, Thunderbird, Continental, Cougar, and Grand Marquis. Specific fitments are detailed in the extensive compatibility table.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

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Specifications

BrandUSA Standard Gear
Part NumberZP FSF9-31
CategoryDrivetrain

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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

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