Ok do I need help or what. I have a 70 9" out of a f-100 upon pulling it apart we have found that the splines on the axle are shot and also the splines in the cluster so my choices. Oh and also the pinion is grooved a bunch.
1.Look for used axles and purchase a trac-loc.
2.Buy new axles and also the trac-loc
3.Buy a whole new rear-end (new to me).
This rear end is a 28 spline which to me does not matter all that much as it will not see hard core power but I was thinking that as long as I have to get new parts I might as well go with the 31 spline (I would have to cut the axle down and find the large lug pattern). I know that I could find an exploder rear and put that in and redrill pattern but this 70 9" will bolt right for my truck . One thing about rebuilding the rear that I have is that I will know what I have and no more guessing.If I am forgetting anything let me know. Thanks Art

 

1970/72 F100's were available with an optional 9" that had a 9 3/8" ring gear, 31 spline axleshafts and 4 pinion traction lok.

The 31 spline axle shafts used in 1973/79 F100/150's will not work in a 1968/72 9 inch.

 

Bill thank you for the info.Now would they still fit in the same housing ?

 

9 vs. 9 3/8: Different carrier (pumpkin).

 

Where can I buy new axles for this rear end ? It measures 29 15/16 +/- from what the person told me and is the large bolt pattern 5 5 3/4.

 

There's no F100 9" with a 5 3/4" bolt circle pattern. Excepting some 1980/83 F100's that have a 4 1/2" bolt circle, all others are 5 1/2."

Some cars with 9's have a 4 1/2" bolt circle, some have 5.00" bolt circle.

Notice in the pic how FoMoCo measures axle shafts.

Column left:

C8TZ-4234-A .. 28 Spline Axle Shaft: 1968/72 F100.

C8TZ-4234-B .. 31 Spline Axle Shaft: 1968/69 F100.

D0TZ-4234-A .. 31 Spline Axle Shaft: 1970/72 F100.

 

ok 5 1/2 I was mistaken anyway the bigger of them. I thought I was wrong once but I was just mistaken

 

Has anyone put 31 spline axles and differential in a housing that originally had the 28 spline ? I see on the 28 and 31 spline there is a 2/16th (1/8) difference in length. Is the spider gear set up 1/8 wider. I think that I will have a couple $'s more in this than I had anticipated Bill I want to thank you for your help.

 

Ok found the axles now to proceed further into the build. I am asking you guys that are into this all the time about what gears I should use. I have an FMX no overdrive and I am running 255 70R 15's. Right now the stock 1955 axle makes the enging sound like it is getting ready to bust at the seams so I woud like to move up as in a 3:25 or 3:50 I have to buy new ring gear and pinion anyway so I only want to do it once so I am asking for some input. When I say move up I mean the numbers move down that's the way we learned back in the long ago. Thanks

 

You got ta love ford for not keeping anything compatible on the 28 spline rear end on the years that I need I see 3 different lengths and 2 different axle end dia. I will win on this one. I did pick up two axles Friday and they are shorter by 1/8 " so does anyone know if I can use them?

Once again thanks for the help.

 

You will no problem putting a 31 spline center section in a housing that had a 28 spline. The axles are different dia. at spline because of the added splines. When you say the new axles are shorter, shorter than the 28 spline?

 

Last chance. ok here we go the housing that I have is as I know out of an f-100 1970 the axles in it were 28 spline and 29 15/16 in length the splines are shot so I have been hunting axles and found some 28 spline but they are 3/16 " shorter my question is will they still work ? I have to go back out to the shop and measure the dia and make sure they are 1 1/4 ". What I was thinking earlier is would a 31 spline center fit in the same housing that I have now but since I would have to shorten the 31 spline axles I will just stay with the 28 spline . I hope that this makes sense . I thank you for you input. The reason I am using this year rear end is it will fit my 55 f-100.

 

Strange and Moser can build you just about anything you want. I hear its reasonable. What i would do, is call strange / moser / dutchman, and order a set of 31 spline axles for your housing, and buy a detroit truetrac to stuff in it. Problem solved.

 

You have to be careful swapping axles, Ford used 2.375 and 2.500 brake offset. This is how much the axle hangs out of the housing. 3/16'' is not a problem as long as it is in the spline area. Do you know what the axles are out of? Moser axles are about 450.00 a pair and they will make any size you need. I have used moser axles many times and they have quick turnaround.

 

I do not know what they are out of but will try to find out tomorrow I do know just by looking that bearing retainer ring is different on each axle .