We sell New and Rebuilt 8" Rear and 9" Rear Ford Third Members.

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9 Inch Ford Rear Applications

9” third members are limited-slip differentials. They are available in either a standard case, nodular case, or an aluminum thru-bolt for street to race applications. Of these Ford rear differentials, either a 28, 31, 35 or 40 spline axle can be used.

All third members come with a new housing gasket, and all trac-lok units come with a friction modifier. Motive or US gear/Strange gears are used in all third members.

For street applications up to 400-450 Hp (small block motors)

Standard case and pinion support:

  • Either a used case (cleaned, glass beaded and painted), or a new case will come to you with all new internal parts including bearings, seal, o-ring, crush collar and nut.
  • Carrier and gears are also new.
  • Available with a new Billet Trac-Lok or Eaton True-Trac.

For street or race applications over 450 Hp ( all big block motors)

Nodular Case:

  • We offer a new aftermarket nodular case with a new Daytona pinion and all new internal parts including: bearings, seal, o-ring, solid pinion spacer and nut.
  • Carrier and gears are also new.
  • Available with a new Billet Trac-Lok or Eaton True-Trac or Detroit Locker.

*Nodular Date code “N” case:

  • We’ll provide you with a used case dated between 1962 to 1970 with proper C5 Daytona pinion support.
  • This unit is cleaned, glass beaded and painted, and comes with all new internal parts including: bearings, seal, o-ring, solid pinion spacer and nut.
  • Carrier and gears are also new.
  • Available with stock trac-lok, new Billet Trac-Lok or Detroit locker.
  • We have a steady changing supply of casting dates available.

The Nodular iron case would have been standard in GT-E’s, 428 Cobra Jets, 429 Cobra Jets, Boss 429 Mustangs, Boss 302 Eliminators and Boss 302 Mustangs.

*The External ”N” did not appear on the nodular cases until October 31 1968

Carriers Explained

  • Trac-Lok: Clutch type differential. Requires Friction Modifier (included), very quiet, works very nice in a street car.
  • Eaton True-Trac: Helical gear type differential, very quiet on the street, recommended for road race applications.
  • Detroit Locker: Mechanical Clutch type differential, aggressive on the street, noisy on turns as this unit unlocks when one wheel is turning a different speed than the other.

Yokes Explained

To properly build a third member and “bolt-in” to your car, we will need to know what yoke your car currently uses.

  • Short or long: measuring from the face of the pinion seal to the face of the yoke, there are two choices 3 ¼” (short) or 4 ¼” (long).
  • Wide or narrow: measure the width of the universal joint or between the tabs in the yoke, there are two choices 3 ¼” (narrow) and 3 5/8” (wide)
  • U joint bearing cap size: measure the diameter of the u joint caps there are three sizes, 1 1/16”, 1 1/8” and 1 3/16”

For more information or help deciding which third member is right for your application please call or contact us here.