8.25 27 or 29 splines...how to tell

Other than the obvious of counting the splines if the axles were out , how do you know when looking at a assembled rear diff which axles it has?

Reason asking for my 93 xj I have found a factory style posi unit for 29 spline axles.

Mine should have 27's if ive read correctly and if its the original rearend in it.

With that being the case Id need to find either axles, or a JY rearend from the local upullit.

Is there a code tag on them or stamped somewhere that would tell ?

Not that I know of. You are correct that you should have 27-spline axles, although if you can find a date code stamped into the housing somewhere (I don't know if that was done or not, so it's just a guess...) that may allow you to see if the rearend has been changed.

I do believe that the axle can be converted, but you'll need a whole carrier to do it - I think the bores for the 29-sp side gears are larger than those for the 27-spline. Can you bore out the side gear bores to accept the larger gears? I don't know - I've not tried it, nor have I compared the two carriers side-by-side to see if there is any significant difference.

Chrysler 8.25 - 27 spline - used 91-96

Chrysler 8.25 - 29 spline - used 97-01

You might try these:
Record the build tag data and take it to your dealership. They might be able to give you info on it.
Or:
Try the same thing with the VIN.

tbburg said:

You might try these:
Record the build tag data and take it to your dealership. They might be able to give you info on it.
Or:
Try the same thing with the VIN.

Click to expand...

That's great advice unless you have a 96. Than the dealer & VIN is useless, ask me how I know.

I would pull a shaft and check them. I have a 91 and found out I have a D35 Non c-clip axle last weekend. Everything pointed towards it being a c-clip until I pulled a shaft. Best to be safe and check.