I recently bought my first XJ, and the rear leafs were shot. So I opted to just lift it instead of putting OEM leafs in it. I used the Rubicon Express 3.5" Super-Ride lift kit, installed with a mechanic buddy at the shop that he works at.

I did a ton of research on it ahead of time and ordered a t-case drop just in case I had driveline vibes... I did. The vibration was (and still is) not noticable between about 0-10 MPH, and gets worse as I go faster/push it harder. I haven't taken it over 30 MPH or so, just to avoid something catastrophic. I put in the t-case drop, which didn't really help it. I then used an angle finder to check to see what my output and pinion angles were looking like, and from my measurements (as best as I could) it was about 2.5 degrees off on the pinon, so I put some axle shims in there to see if that would help, but it really didn't do anything. I also replaced the U-joints, still did nothing.

My buddy has a friend that has done multiple lift kits on Jeeps and other vehicles. He visited the shop the other day, so my buddy let him take it for a spin to help diagnose. He seemed to be confident that it was a bad ring and pinion. All of the research that I have done has not brought me across this issue before, so I wanted to see if anyone has come across it.

I essentially am weary to throw new gears in it (as I know it is expensive as well as difficult). I also know that SYE's commonly fix driveline vibrations, but if making the angles closer didn't help it, wouldn't that indicate that putting an SYE in wouldn't really remedy the problem?

I just don't know where I want to dump the money essentially. I was hoping someone has had a similar situation to mine and been able to fix it... At this point, I am regretting even putting the lift in to begin with, so frustrating not being able to use it.

I should also put here, 2000 XJ Sport, C 8.25 rear, NP241 TC. Just in case people were wondering.

Thanks