First off, I want to say hi. I have an 89 rs with a 305 tbi, t5 and 3.08 gears. My pinion bearings are shot. A friend of mine gave me a posi unit out of his 99 ss will this work in my rear axle? I hear that they switched from 26 to 28 spline axles in 89. How do I know which I have without tearing it apart? Is there any differance between the gears in a 7.5 and a 7.625? I have a 3.73 ring and pinion for a 7.5. Any help would be greatly appreciated. Thanks in advance, Steve

 

Answer to the axle spline qwestion: 1989 is correct for the changeover from 26 to 28 splines and your chances are just 50/50 you have the 28 splines. Sorry you are going to have to open it up and check the shafts. 7.5 &7.625 dia gear are interchanable with no differences and 3:73 gears can be used.

 

So as long as i use the 28 spline axles the posi unit out of the 99 ss will work with no other modifications.

 

The 4th gen Limited Slip carrier & 3:73 gears will replace your old open 2-series carrier & 3:08 gears. All you should need is a rebuild kit. However; a gear change is NOT a DIY type job unless you have experience with it. You can screw up big time and you will wish you never opened that rear diff up.

 

I have done many rear axle rebuilds. mostly in the first grand cherokees. I just didn't know exactly which parts interchanged. Thanks for the info.

 

IIRC the 10 bolt is really similar to the Dana 35. At least from a reliability stand point, lol.

 

what is IIRC? ive seen it before, but dammed if i know what it means.

 

If I Recall Correctly