Rear axle identification

[Hightower]

I didn't find an axle tag on my rear axle only a cast brand "61" or "19" at the bottom of the axle housing. Does this help for the axle identification?

 

[Carolina_Mountain_Mustangs]

I didn't find an axle tag on my rear axle only a cast brand "61" or "19" at the bottom of the axle housing. Does this help for the axle identification?

Without the tag you will have to dig deeper. You can look at the actual housing from the back and if it is one smooth sphere you have an 8" rear. If there is a bump out you have a 9" rear.

If you jack up both rear wheels and turn one wheel if the other turns also you have a traction loc or maybe even a Detroit locker.

You can have 28 splines on the axle or 31.

This site has the most complete info on the Ford numbers I have found.

http://mustangtek.com/differential/Differential.htm

You can rotate the tire and count the drive shaft rotations to get the ratio. Videos on youtube I am sure.

Forgot to tell you when in the mustangtek site you can click on the pictures of the parts and expand them. Also take note of the super rare Hone-O-Drive that he has a picture of. It was a two speed rear that almost made production. A few were built for testing and got out. Articles in some of the magazines back in the day.