Is there a tech area that lists specs?

Axle spline count should be 28 on all Mustangs until 2005 when Ford went to 31 spline axles.

I'm 99.9% sure that the 2005 GT's were the first Mustangs with 31 spline axles from the factory, unless the '69 - '72 428 SCJ's also had them.

I recall that the addition of the 31 spline axles for the 2005 V8 cars was kind of a selling point for Ford at the time. The V6 Mustangs stayed with 28 spline axles.

You are right...a good spec sheet for each generation of Mustang would be a good addition to this site...possibly gathered by the users of each generation Forum?

It could even be done in the form of a Wiki...hmmm:
Ford Mustang - Wikipedia, the free encyclopedia

And:
Fifth-generation Ford Mustang - Wikipedia, the free encyclopedia

From the Fith-Generation Wiki (under the "Mustang GT" heading):
"The current Mustang GT also comes equipped with a limited slip differential complete with the same carbon-fiber clutch discs used in the 2003 to 2004 SVT Cobra and the 2007 Shelby GT500. The differential is designed for the 31-spline axles and the 8.8-inch (220 mm) ring gear."

This doesn't specifically say that it is a new feature, but I didn't see it in the "4th Gen" section.

The Car Craft article that Welder linked to above states that the axles became 31 spline in '94 and I haven't been able to find anything directly contradicting that on several sites (Ford Racing Parts, PartsAmerica.com), so i give up.

I would bet that a big axle supplier like Moser or Strange could tell you in a second.

Let us know when you find out. I'm curious now...