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Complete Third Member and Center Sections

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Complete Third Member and Center Sections

Instead of piecing one together and hoping it all fits, get a complete third member assembly with one part number from Summit Racing Equipment!

A complete third member...

Instead of piecing one together and hoping it all fits, get a complete third member assembly with one part number from Summit Racing Equipment!

A complete third member assembly (sometimes called a center section) includes everything you need to connect your driveshaft to your rear axles. They typically include a U-joint style yoke to connect to your driveshaft, ring and pinion gears, differential carrier, and a case. They’re also available with spools for maximum traction.

Whether you need a lightweight center section for racing, a trail-tough third member assembly for off-roading, or a stock replacement for fixing up your...

Instead of piecing one together and hoping it all fits, get a complete third member assembly with one part number from Summit Racing Equipment!

A complete third member assembly (sometimes called a center section) includes everything you need to connect your driveshaft to your rear axles. They typically include a U-joint style yoke to connect to your driveshaft, ring and pinion gears, differential carrier, and a case. They’re also available with spools for maximum traction.

Whether you need a lightweight center section for racing, a trail-tough third member assembly for off-roading, or a stock replacement for fixing up your daily driver, our search tools make it easy to find the right third member assembly! For example, if you’re your looking for a Ford 9 inch third member, you can filter by case style (Ford, Chevy, Toyota, etc.), axle spline count, gear ratio, and more! With hundreds of applications available, Summit is your go-to source for complete third member assemblies.

Differential Identification Charts


Not sure what you’ve got back there? Visit Summit’s Help Center for our rear-end identification guides.

Even More Complete!


Need the matching axles, too? Consider a complete rear end assembly!

Top Brands


No third party resellers here—Summit Racing only partners with trusted manufacturers like Moser, Strange Engineering, Trail Gear, and Currie Enterprises.

Not Showing Customizable Items. View Customizable Items.

Individual Parts

Results 1 - 25 of 475

Third Member, 3.70:1 Gear Ratio, Currie TwinTrac, 31-Spline, Nodular Iron Case, Big Bearing Pinion Support, 1350 Yoke, Each

Part Number: CUR-CE-9CT370S50

5.0 out of 5 stars ( 2 )

Estimated Ship Date: Today

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Third Member Complete Assembly, Ford 9 in., 3.50:1 Gear Ratio, TwinTrac, 31-Spline, Nodular Iron Case, Big Bearing Pinion Support, 1350 Yoke, Each

Part Number: CUR-CE-9CT350S50

5.0 out of 5 stars ( 2 )

Estimated Ship Date: Today

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Third Member, 4.11:1 Gear Ratio, Currie TwinTrac, 31-Spline, Nodular Iron Case, Big Bearing Pinion Support, 1350 Yoke, Each

Part Number: CUR-CE-9CT411S50

4.0 out of 5 stars ( 2 )

Estimated Ship Date: Today

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Third Member, 3.89:1 Gear Ratio, Currie TwinTrac, 31-Spline, Nodular Iron Case, Big Bearing Pinion Support, 1350 Yoke, Each

Part Number: CUR-CE-9CT389S50

5.0 out of 5 stars ( 3 )

Estimated Ship Date: Today

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Third Member Complete Assembly, Ford 9 in., 31-Spline, Nodular Iron Case, Detroit Truetrac, 3.50:1 Ratio, Daytona Pinion Support,1350 Series Yoke,Each

Part Number: MSR-3MST31AN350

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 35-Spline, Nodular Iron Case, Wavetrac, 3.50:1 Ratio, Daytona Pinion Support,1350 Series Yoke, Each

Part Number: MSR-3MNW35AA350

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 31-Spline, Aluminum Case, Detroit Truetrac, 3.50:1 Ratio, Daytona Pinion Support, 1350 Series Yoke,Each

Part Number: MSR-3MAT31AA350

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 31-Spline, Aluminum Case, Detroit Truetrac, 3.25:1 Ratio, Daytona Pinion Support, 1350 Series Yoke,Each

Part Number: MSR-3MAT31AA325

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 33-Spline, Nodular Iron Case, Spool, 4.29:1 Ratio, 10-Hole Pro Pinion Support, 1350 Series Yoke, Each

Part Number: MSR-3MNS33AP429P

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 31-Spline, Nodular Iron Case, Detroit Truetrac, 3.50:1 Ratio, Daytona Pinion Support,1350 Series Yoke,Each

Part Number: MSR-3MNT31AN350

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 35-Spline, Nodular Iron Case, Detroit Truetrac, 4.11:1 Ratio, Daytona Pinion Support,1350 Series Yoke,Each

Part Number: MSR-3MNT35AA411

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 28-Spline, Nodular Iron Case, Trak-Lok, 3.70:1 Ratio, Daytona Pinion Support, 1350 Series Yoke,Each

Part Number: MSR-3MNC28AA370

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 28-Spline, Nodular Iron Case, Trak-Lok, 3.50:1 Ratio, Daytona Pinion Support,1350 Series Yoke, Each

Part Number: MSR-3MSC28AN350

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 35-Spline, Nodular Iron Case, Spool, 3.89:1 Ratio, Daytona Pinion Support, 1350 Series Yoke, Each

Part Number: MSR-3MNS35AA389

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 31-Spline, Nodular Iron Case, Yukon Trak-Lok, 3.70:1 Ratio, Daytona Pinion Support, 1350 Series Yoke,Each

Part Number: MSR-3MNC31AN370

Not Yet Reviewed

Estimated Ship Date: Today

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Third Member Complete Assembly, ZR12, TrueTrac, 3.73:1 Gear Ratio, 33-Spline, Aluminum Case, 1350 Yoke, Each

Part Number: DSR-070650373DS

Not Yet Reviewed

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FN988 STD CASE 31 SPL TT 4.10 RATIO 1350, With REM Finishing

Part Number: DSR-070880410DSR

Not Yet Reviewed

Estimated Ship Date: Nov 24, 2026 if ordered today

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Estimated Ship Date: Nov 24, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 31-Spline, Nodular Iron Case, Trak-Lok, 3.25:1 Ratio, Daytona Pinion Support,1350 Series Yoke, Each

Part Number: MSR-3MSC31AN325

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

FORD 9'' 3.50 N GEAR 31 SPLINE TRUETRAC

Part Number: DSR-90-20015

Not Yet Reviewed

Estimated Ship Date: Nov 24, 2026 if ordered today

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Estimated Ship Date: Nov 24, 2026 if ordered today

FN988 TA CASE 31 SPL TT 3.31 RATIO 1350

Part Number: DSR-070881-331DS

Not Yet Reviewed

Estimated Ship Date: Today

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Third Member Complete Assembly, Ford 9 in., 35-Spline, Aluminum Case, Spool, 4.11:1 Ratio, 10-Hole Pro Pinion Support, 1350 Series Yoke,Each

Part Number: MSR-3MAS35AT411P

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 31-Spline, Aluminum Case, Detroit Truetrac, 3.70:1 Ratio, Daytona Pinion Support, 1350 Series Yoke,Each

Part Number: MSR-3MAT31AA370

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 31-Spline, Nodular Iron Case, Detroit Truetrac, 3.00:1 Ratio, Daytona Pinion Support,1350 Series Yoke,Each

Part Number: MSR-3MNT31AN300

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 31-Spline, Nodular Iron Case, Detroit Truetrac, 3.89:1 Ratio, Daytona Pinion Support,1310 Series Yoke,Each

Part Number: MSR-3MNT31BN389

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today

Third Member Complete Assembly, Ford 9 in., 31-Spline, Nodular Iron Case, Detroit Truetrac, 4.57:1 Ratio, Daytona Pinion Support,1350 Series Yoke,Each

Part Number: MSR-3MST31AN457

Not Yet Reviewed

Estimated Ship Date: Dec 21, 2026 if ordered today

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Estimated Ship Date: Dec 21, 2026 if ordered today