Ford 9" rearend spline count

[cathyanderson]

Hey, does anybody out there know how to find out howmany splines in a rear end out of a 1978 1/2 ton Ford truck without taking hte axle apart?

thanks
Jimmy

 

[Mac]

Is there a tag on the rear? I know on the cars with the 9", the 98% rule is that if there is what looks like a cast-in indentation that looks like a dog bone on the rear/outside end of the axle, it's a 28 spline. If there is a center drill point in the middle with two other 1/2" holes about 1 1/2" apart, should be the 31 spline.
Dave

 

[Rico]

Ford used either 28 spline or 31 spline axle shafts with the nine inch, the eight inch came only in 28 spline, as did the majority of nine inch car applications.For the most part eight inch and nine inch car axle shafts will interchange between housings of the same width,spline count and bearing size (ie. 8" 67 Mustang 28 spline axle shafts will work in 9" 67 Mustang housing, etc.).A method to identify 28 spline axle shafts can be by looking at the center brake hub area, a rectangular slot in the center will indicate 28 spline axles.The 31 spline axle shafts will have a different appearance, with one small center chamfer and two outer holes in the center hub, however, 28 spline shafts can also appear like this to, so it does not always indicate 31 spline shafts (see photo below). Early axle shafts of the 28 spline variety cannot be shortened, due to either a reduced diameter between spline end and bearing end (early Mustangs,Fairlanes, Falcons etc.), or because of a tapered shaft which doesn't allow for re-splining (early full size).It appears starting around 1967 the 28 spline shafts became more solid and the shaft diameter increased along the entire length, so shortening is possible and they can be be resplined to their original 28 count.Most 31 spline shafts can be shortened and resplined with no problems.

Take a look at this link Mac gave me. This is extemely valuable information about the Ford 9in.

http://www.kevinstang.com/Ninecase.htm

Scroll a little more than half way down to where the pictures of the axles shafts are.
You probably will have to take a wheel off and that's it.

 

[Mac]

That is a really good source of info and does explain that not all 9" rear ends are capable of high power.
Mac