rear 28/31 spline

[badmustang]

hi i have a 351-w 1969 mustang fastback and have a tracktion lock
diff but i want to order a new diff and ther are 2 optins a 28 or 31 spline witch
1 do i have... what can standaard on the 1969..
thanks jay (the neterlands)

 

[rbohm]

likely you have a 28 spline axle, but count the splines to be sure.

 

[jbuening]

Typically if you look at the end of the axle that is visible in the center of the brake drum, the 31 spline will be smooth with a couple indentations and a 28 spline will be dished. See pic below from Ultrastang's website

 

[badmustang]

hi thanks for your help and pictures.

 

[D.Hearne]

Don't base your spline count though on the axle ends, that method isn't 100% accurate. More than likely there's a 99% chance you've got 28 spline axles, unless some previous owner swapped em.

 

[danny clemens]

I'd definately pull one axle and count the splines. It should be 28 spline but you never know.

I have a set of axles from a 59 Ford that have the double indentions in them and they're 28 spline.

 

[D.Hearne]

I'd definately pull one axle and count the splines. It should be 28 spline but you never know.

I have a set of axles from a 59 Ford that have the double indentions in them and they're 28 spline.

Right, the 28 spline axles come in two versions. The big bearing ones taper down just before the carrier ends. The bearing for the 28 and 31 spline are the same in this case.

 

[bnickel]

lincoln versailles rear are this way as well, 28 spline but the axle flange looks like a 31 spline axle.

a 69 with a 351w would have come from the factory with 28 spline axles but it is possible that someone in the past swapped in a 31 spline diff and axles.

 

[ultrastang]

hi i have a 351-w 1969 mustang fastback and have a tracktion lock
diff but i want to order a new diff and ther are 2 optins a 28 or 31 spline witch
1 do i have... what can standaard on the 1969..
thanks jay (the neterlands)

Assuming your Mustang's rear end/axles/differential has never been swapped out, it should have 28-splines. If the Mustang had come with a 351C or larger displacement engine, it would have come with 31-spline axles.

 

[danny clemens]

Assuming your Mustang's rear end/axles/differential has never been swapped out, it should have 28-splines. If the Mustang had come with a 351C or larger displacement engine, it would have come with 31-spline axles.

I've heard two different stories on the 69 390. One that they did have the 31 spline and another that said they did not have the 31 spline. I'm not disputing what you're saying but have you actually saw a 69 390 car that has 31 spline axles? I've never pulled axles from one so I couldn't say. If they do have them is it both the X code and S code or just the S?

 

[Grabber70Mach]

Assuming your Mustang's rear end/axles/differential has never been swapped out, it should have 28-splines. If the Mustang had come with a 351C or larger displacement engine, it would have come with 31-spline axles.

He said he had a 69. I always thought that the Cleveland was not available until 70.

 

[Grabber70Mach]

double post

 

[73vertstang]

Check the housing, there should be a metal tag attached to one of the bolts. the code on the tag will tell you how many splines, gear ratio. You might get lucky!

 

[65ShelbyClone]

Don't base your spline count though on the axle ends, that method isn't 100% accurate.

The '57 axles I have are a prime example. Flat hub center, yet 28 splines.

A last-ditch option is to pull one of the axles and count the splines.....

 

[D.Hearne]

Check the housing, there should be a metal tag attached to one of the bolts. the code on the tag will tell you how many splines, gear ratio. You might get lucky!

Where's the spline count on the tag? I've never seen that part. Gear ratio and lock or no lock plus the code for the application, but nothing that indicates spline count.

 

[73vertstang]

I got lucky when I pulled the Engine, transmission and the drive shift. I was poken around the front of the housing and found the tag under 2 inches of muck.
The tag had WES 2.75 and some other stuff (I don't remember off hand) Looked the WES code up in one of my manuels and sure enough there it was 28 spline 2,75 gear ratio. I will follow up when I get home with some more info

 

[73vertstang]

Just to follow up, In Mustang restoration Guide by Tom Corcoran and Earl Davis, page 410-411 there is several charts listing the codes and number of splines. For example: 72-73 - WES-AD2 / Axle ratio 3.25 / Ring Diameter 9" / Axle Splines 28.

71/72 - WFD - D2 /AR 3.91/ RD 9" / AP 31

Hope this helps!