ViperSRT

I picked up a 2000 WJ Grand Cherokee. Had a few minor issues that needed correcting. I went ahead and put 3" spacers on while correcting other items. I had only driven it once before installing the lift kit. I am getting a vibration that feels like its coming from the the rear end when I first start out. Only does it at shift points up to third gear the goes away. I have a 42RE auto with a Dana 35 2WD. I am thinking that maybe it has to do with the lift kit and maybe the U joints are not aligned now since the lift but I didn't think that would have made that much on a difference. Anyone else able to raise theirs without any issue?

peep

I replaced the lower control arms on our 02 WJ to eliminate a vibe. The arms looked good but the bushings were wallowed out and sloppy.
You could unbolt the lowers to check.
At this time I do get a bit of rear clunk on rough surfaces, so suspecting a rear upper control arm service is next.
This all assuming your rear shocks and drive shaft u joints are good.
I had cheaper Monroe Magnum shocks on the WJ for a few months last spring. Poor performance and longevity,waste of money. Replaced with Monroe Reflex good quality shocks and way better and still working good.
On our ZJ I also run Monroe sensi trac and sensi trac load assist with very good results on 31's.
I have had vibrations from the front drive shaft on the WJ, it has a CV joint rather than a double card. joint. I unbolted that, disassembled, cleaned and relubricated, couple years ago, no more vibe andno trouble there since.
I do also have a Hyundai, yes a mental lapse and slip to the dark side,but hard to argue with 50 mpg. On my winter rims, I have one out of round, doesn't run true by 0.020", and I can feel it up to about 50 mph, then smooths out some. Not too worried as these are the winter rims and we only get 14 months of winter in Canada each year. But you may have a rim out of round or bent on your WJ or a rear bearing causing some wheel run out.
Hope you find the Gremlin soon.