DSE FN988 Assembled Center Section - 3.31 Ratio / 31-Spline Truetrac - 070880-331DS
Bring together the proven packaging of a traditional Ford 9-inch housing and the quieter, more efficient operation of an 8.8-inch gearset with the Detroit Speed 070880-331DS FN988 Assembled Center Section. This patent-pending Detroit Speed design allows an 8.8-inch center section to bolt directly into a traditional 9-inch housing, creating a performance-focused alternative to a conventional 9-inch center section. This version comes completely assembled with a 3.31 gear ratio, 31-spline Eaton Truetrac differential, and 1350 forged-steel pinion yoke with U-bolts.
The 070880-331DS is built around a high-strength nodular cast iron case with forged alloy-steel carrier bearing caps for serious power handling. Detroit Speed equips the assembly with a premium ring and pinion secured by safety-wired ARP ring bolts, a solid pinion preload spacer, and internal oil channels that continuously lubricate the pinion bearings. Threaded jack-bolt holes in the mounting flange help ease center-section removal from the axle housing, while integrated mounting holes accommodate bolt-on accessories. Designed and engineered by Detroit Speed and made in the USA, the FN988 gives builders access to compatible 8.8-inch gears, differentials, and spools while retaining compatibility with a traditional 9-inch housing.
Specifications
- Manufacturer: Detroit Speed
- Part Number: 070880-331DS
- Product Type: Differential Assembly
- Case Series: FN988
- Carrier Style: Ford 8.8-inch
- Case Material: Nodular Iron
- Differential: Eaton Truetrac
- Axle Shaft Spline Quantity: 31
- Gear Ratio: 3.31
- Yoke Style: 1350
- Pinion Yoke: Forged Steel
- Yoke Hardware: U-Bolt Kit
- REM Polished: No
- Housing Compatibility: Traditional Ford 9-inch housing
- Emissions Code: 4
- Manufacturing: Designed and engineered by Detroit Speed and made in USA
Features
- Patent-pending FN988 design combines Ford 8.8-inch differential components with a traditional Ford 9-inch housing
- Designed for quieter and more efficient operation than standard 9-inch components
- 3.31 gear ratio
- 31-spline Eaton Truetrac 8.8-inch differential
- High-strength nodular cast iron case
- Premium ring and pinion with safety-wired ARP ring bolts
- Internal oil channels provide continuous lubrication to the pinion bearings
- Solid pinion preload spacer
- Forged alloy-steel carrier bearing caps
- 1350 forged-steel pinion yoke with U-bolt kit
- Threaded jack-bolt holes in the mounting flange help ease removal from the axle housing
- Case includes mounting holes for bolt-on accessories
- FN988 case is compatible with 8.8-inch gears, differentials, and spools
- Designed and engineered by Detroit Speed
- Made in USA
Fitment Notes
The Detroit Speed 070880-331DS is a universal FN988 center section rather than a year, make, and model-specific component. It is designed to bolt into a traditional Ford 9-inch housing while utilizing Ford 8.8-inch differential components. Detroit Speed specifies that FN988-specific axle shafts are required and the driveshaft will need to be shortened. Verify the complete rear axle and driveline combination before installation.
FAQs
What makes the Detroit Speed FN988 different from a traditional Ford 9-inch center section?
The FN988 is designed to bolt into a traditional Ford 9-inch housing while using Ford 8.8-inch gears and differential components. Detroit Speed engineered the system for quieter and more efficient operation than standard 9-inch components.
What gear ratio and differential are included with 070880-331DS?
Detroit Speed 070880-331DS comes assembled with a 3.31 gear ratio and 31-spline Eaton Truetrac 8.8-inch differential. It also includes a 1350 forged-steel pinion yoke with U-bolts.
Does Detroit Speed 070880-331DS require special axle shafts?
Yes. Detroit Speed specifies that FN988-specific axle shafts are required. The driveshaft will also need to be shortened for installation.
Why Buy Detroit Speed from Beefcake Racing?
Beefcake Racing is your source for Detroit Speed rear axle, suspension, chassis, and drivetrain components for serious street, pro-touring, autocross, and track builds. An FN988 rear-end setup requires the correct combination of center section, axle shafts, housing, and driveline components, and our team can help you put together the right package. Questions about Detroit Speed 070880-331DS or your FN988 rear axle setup? Email sales@beefcakeracing.com or call 1-855-827-7223.
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