Eaton Detroit TrueTrac 9" 31 spline
 

I have an open 9" N 31spline axle from a 70 Fairlane under my 55 F-100. I'm putting in a new engine which will give me around 500HP and I want traction. When looking around I've decided to go for the Eaton Detroit TrueTrac ( alot better roadability that a Detroit locker), but even though the part nr 913A586 should fit, I see there are a number of different types on E-bay.I especially want info on the "slim" one and the "thick" one. Which works for my axle?? Are there differences between early 9" and late 9"? The thick one might be for 1980 and later Ford axles, but I'm not sure.

...differences between early 9" and late 9"?
 

Well...the short answer is...YES!


"Which works for my axle?"...uuuhhhhh....it's like this...:confused:...

Got any idea about;

-axle bearing size?

-carrier bearing size?

-axle flange bolt pattern?


HOW do you know that the axle assembly was originally out of
a '70 Fairlane?....:-huh...

Got any photo's of this bad-boy to post?....we LOVE pictures......

I'd really like to see pic's of the infamous ''N" on the hog's-heads...}>...

Is this assembly already torn down?...got any pic's of the axle shafts
themselves?


-

The axle is in the truck and in use( during the summer-I live in Norway so I don't drive in the winter)
The axle tag said WEC-S OFB
3.25 9 890A

which desiffers to 69 Comet, 69-71 Fairlane, 70-71 Montego or a 72 Torino.
It has the big N and should be a 9" 31 spline case.I haven't opened it up yet ( if it works, don't ****with it) and therefor the questions. Hoping someone had the same axle and could tell me.