Ok, I just created an account because I want some help on an issue I am having with my driveline on my 2001 XJ Sport.
I recently put a 3inch rough country suspension lift (new coils, new leafs, new shocks.. I know its a cheaper lift) as well as some new 31inch BGF KO2's. I now have vibration from speeds 5mph-30mph in the rear and from 30mph and above I get back vibration or "whrrrring" noises (sounds like the driveline) when I just barley release the gas pedal. The sounds also seems much more consistent when i am in 4 wheel drive at speeds 30mph+.
I have heard I might need a T-Case Drop, Shims, or the best option (SYE and new shaft).
Thoughts? Looking to fix this soon because the noise is very prominent and it vibrates a good amount around town.

Thanks.

 

T-case drop = bandaid
SYE = the right way to do it

SYE will most likely also require you to shim the axle. A new driveshaft is a must like you said.

 

Space down your T/C cross member about 1/4" with a few washers. That was all I had to do to resolve the dl vibes when I installed a 3" kit.

 

Yep, that is what I did. I kept adding washers till the vibration stopped. I end up spacing about an inch. I did swap out those bolts with grade 8 bolts. Had install my kit 7 years ago. Still no problem with vibration. I run 31x 10.5 tires.

 

Sye fixed mine at 4.5”