So it actually works, but something is wrong ha!

With the front driveshaft in it vibrates while driving in 2 wheel drive. Take the shaft out and it stops. Drive shaft is balanced even tried another shaft from another cherokee.

What do I need to replace/rebuild?

 

Check the u joints and the axle joints

 

Are you lifted? Adjustable arms?

 

Yeah 3" with LCA

 

Probably have an incorrect pinion angle then.

 

It didn't used to do it and I drove it a good 10k miles after i owned it with 250k on the dial, why now?

That aside, what do you do to fix pinion angle?

 

Could be a combination of a bad pinion angle causing premature failure of driveshaft U-joints.