Originally Posted by drl650
I meant the uppers, so I need to shorten the uppers to lower my pinion. The reason is, I have a slight vibration during excelleration, It is hardly noticable but I feel it..This lift has been on for a couple of years installed before I got it. The rear shaft I rebuilt with new u joints as one was bad so I replaced all of them. This is on my Rubicon with a 4.5" RE lift. Thanks.
with 4.5" of lift you need a double cardan driveshaft (called a CV shaft).
While Rubicon's NV241OR's are fixed flange output, they do not come with a double cardan rear driveshaft from the factory. With a double cardan driveshaft, you will point the pinion up, typically directly parallel to the driveshaft. That will change the position of the track bar and rear shocks, both issues you will also need to address.