Anyone know what spline count I would have on the axle shafts in a 65 4x F100 with a 9" 08 axle code on the warranty tag? Its got a 5600 GVW.

 

B7TZ-4234-A (replaced B7C-4234-A) .. 9" Axle Shaft - 28 splines - right/left is the same / Obsolete

Applications: 1957/67 F100.

 

Thanks you sir!!!

 

The trucks didn't get 31-spline axles until the '68-'72 Bumpsides came along in some F100s with a Ford 9-3/8" rear end. The 9-3/8" rear is very similar to the 9-inch rear but not the same thing as a 9-inch.


An "08" axle code would be for a 28-spline, open (single track), 2-pinion differential with a 3.50:1 gear ratio.

 

I'm correct to asmume my 08 code axle is a 9" not a 9 3/8"? Would any 9" third member with 28 splines drop in?

 

Yes, your truck would have had a 9-inch, since 9-3/8" rear ends weren't put into some of the F100 trucks until starting in '68.

A 9-3/8" 3rd member is easily identifiable from a 9-inch 3rd member. The 9-3/8" 3rd member will have two widely spaced vertical ribs on the front with a top horizontal rib that curves downward on the left side --as seen in the following photo.



A conventional 9-inch 3rd member (after about 1960/'61) will look like this.



A Ford 9-inch N-case (nodular iron --the ultimate in Ford 9-inch 3rd members for strength) will have two vertical ribs more closely spaced than the ribs on the 9-3/8" 3rd member but, the horizontal ribs on the N-case don't curve downward at the ends --31-spline 4-pinion Traction-Lok differential 3.50 geared Daytona N-case 9-inch 3rd member pictured on the right in the following photo. My old "08" axle code '69 F100 C7AW-E casting 28-spline single track 3.50 geared 3rd member on the left.



From 1957 to about 1960/'61, the Ford 9-inch 3rd members were cast from a weaker gray iron material. These 3rd members were more prone to breaking where the input driving pinion housing is. The 3rd member casting numbers for any of the 3rd members mentioned here can be found on the inside of the 3rd member, next to the right hand differential side bearing stand.

The weaker gray iron 9-inch 3rd members look very similar to the N-cases but, there are notable outward differences between them if you know what to look for. The more undesirable gray iron 9-inch 3rd members will look like this.



If you come across a 9-inch 3rd member you think is an N-case and you see these letters inside it (WAR, WAA or WAB), it's not an N-case. It's an older gray iron unit.



Any 9-inch 3rd member (car or truck) will fit in any 9-inch rear end housing. The differential spline count just has to match the spline count of the axles for the particular rear end housing the 3rd member is being used with. The companion flanges (where the driveshaft attaches) are generally longer on passenger cars and shorter on the trucks.