Secrets of the Ford 9-Inch Rear Axle

[Bob Riebe]

Fascinating as there are companies now making much stronger new versions of the GM, Chrysler and Dana rear-ends but the Ford is one one gear-heads use at least nine times out of ten.
The last bit about NASCAR shows why NASCAR and any business they had to help sell cars went away a long, long time ago.

https://www.macsmotorcitygarage.com/secrets-of-the-ford-9-inch-rear-axle/#more-81728

[Argent 88]

Eaton made that for Ford.

[Argent 88]

Eaton or Dana made that for Ford.

[Bob Riebe]

Eaton made that for Ford.

Eaton makes differentials that fit in Ford third members; Ford made the third member that a differential goes in.
Eaton makes the Detroit Locker but also makes the Posi Limited Slip differential among others.
Ford made  the nine inch till they stopped and after-market kept on making new ones.
Dana third-member is a Salisbury type, Ford 9 inch is not.

There are several reasons the 9-inch enjoys such a strong following. The removable third member makes gear changes much easier than Salisbury-style (Dana) axles. The use of a removable pinion support and spanners instead of carrier shims makes gear setup easy. And there are a nearly infinite number of gear ratios available for the 9-inch, from as high as 3.00 and as low as 6.50. The removable third member also means that the sheetmetal housing is not only lighter than a comparable Dana axle but is easier to weld brackets to for your link suspension since you do not have to contend with a cast centersection.

https://themotorhood.com/themotorhood/2015/12/8/the-ultimate-guide-for-diff-buyers-part-i
https://themotorhood.com/themotorhood/2015/12/8/the-ultimate-guide-for-diff-buyers-part-ii

[Lloyd Smale]

9 inch ford IS THE REAR END others are measured by. No doubt about it. A dana 44 is near as tough but back in the day before overdrives i knew guys that raced there cars that took advantage of the ability of a 9 inch to swap gears so easily. In less then a 1/2 hour you can go from a 343 to a 488. Now with ODs you can run steeper gears all the time and with todays cars your computer is calibrated to the gear ratio so if you swap them you also have to reprogram. So it just isnt done much anymore. I remember guys back in the day that carried a third member in there trunk with there slicks. Ive seen them swapped out right on the side of the road. Stock car guys loved them too. They could easily in the pit change ratios to fit the track conditions.

[Argent 88]

Eaton also made a lot of the transfer cases for 4X4 vehicles. And a lot of PTO's for winches and pumps.