2018 XJL, 3.0, AWD, 125k Miles.

Started noticing rattling/marble nose that comes and goes depending on conditions. Immediately suspected the center/carrier bearing.

After a few days, I began to notice vibration throughout the car getting worse. It starts at about 30mph, eased off somewhat after 40, then started coming back around 60. (I'm wondering if the drifting in snow without traction control and having fun might have been a factor haha, since sometimes you can still feel something either the brakes engage and destroy the fun when angle is too great (haha).)

Raised it up on jacks, ran it, front sensor freaks out due to garage door (it's cold as hell here, but i'll try without the door shut.), and even with traction control OFF - either the Diff/ABS/front sensor causes issues and prevents testing.

Center bearing didn't have any rips, but the front of shaft that connects to the transfer case was tore. I also could hear a noise sounding exactly like the noise under center console that would come and go, when i tapped my fist against the driveshaft right in front of the center bearing, inside the part of driveshaft where the diameter suddenly gets wide.

Anyways, I ordered a used driveshaft from a 50k Miles XJL AWD 3.0 and after a nightmare (and possibly harming the diff flange where the rear of driveshaft connects (theres a rubber and metal ring attached to diff flange) after so many accidental swings and MAP gas throughout frustration and hours of hammering, the driveshaft finally came out.

The center bearing only spins about 180 degrees, and sounds like a bad bearing.

New (used) driveshaft goes in, I left the exhaust out for now (sounds like a shitty truck now lol), and after having to jump the car, went for a drive. at about 33mph, vibration suddenly starts badly, and this time doesn't even disappear without throttle until speeds slow back down. It was late, loud, and need more time to speed up and see how bad it gets.

I noticed:
- Differential mounts have play it seems
- Transmission mount can move with pray bar a bit
- Driver side inner cv axle has a little play when forced up and down by hand

What do you gentleman think? Maybe I need to make sure driveshaft is balanced even though the two places I called can't do jag driveshafts. Maybe I missed something when installing driveshaft? Maybe I made it worse by hammering the diff flange and destroying the rubber kind of? Strong driveshaft now adds more force to mounts/inner axle? I'm getting pissed.