Axles splines

[Lou]

Do all Ford 9 inch limited slip differentials use 31 spline axles? I think the unit  is out of a 66 Ford station wagon. I have a bad wheel bearing and have a set of 28 spline axles with new bearings on them I would like to use and save some money.

[lalessi1]

I am not positive but I think "traction lock" differentials came in both 28 and 31 spline versions. I am pretty sure you can buy either aftermarket. I am in the investigation process so I think this is a great question and I am looking forward to more knowledgeable input at this point as well. 

[gasman826]

Yep, Traction Lok in either 28 or 31 spline format.

[pepfalcon]

also detroit lockers.

[Hoosier Hurricane]

To further muddy the waters, most (but not all) 31 spline axles have the large bearing, and some 28 spline axles have the large bearing also.   John

[gasman826]

also detroit lockers.

Right.  Detroit Lockers began appearing in OEM special applications ('63-'64ish 427 Galaxies maybe others) but nearly all with 31 spline.  After market Detroit Lockers are certainly available in 28 spline and even for 8' rear ends.

[Lou]

Thank you everyone, so I concluded that I'm pulling the axles and counting the splines. This just became a later winter project, thanks again guys.

[SkylinerRon]

31 spline axles are larger in diameter than 28's.
28's will spin around inside 31 spline side gears.
The 66 rear may be a 9 3/8" unit.
Goodluck,
Ron.

[RICH MUISE]

Lou...I think it's posible that even if the axels are the same the bearing could be big or small...so another variant that could bite ya!

[rmk57]

Not sure it would make any difference but depending on if it's Fairlane wagon it could have 8 inch axle.

Galaxie always used 9 inch rear axles.

[SkylinerRon]

Some 1966 up big cars and trucks used the odd ball 9 3/8" rear.
Generally big wgns, 428's, limitedslips and F-150's had them.
They were all 31 spline and 3.50 was the highest numerical gear available.
Looks like a 9" externally.
Goodluck,
Ron.