1995 Other Jeep Models Possible Drive Train problem

I bought this Jeep used. It has full time 4wd, so it is either 4WD High, Low, or Neutral. When purchased the rear drive shaft was out so I got the Ujoints and put eveyrhting back together (work done by someone else) on my wa y home I blew the plug out of the rear diff. Turns out the wheels on the back were 2 inches larger or small than the front, therefore the fulltime 4wd was overworking the rear dif because of the different tire rotation speeds. Now it was all rebuilt and checked over by a drive train specialist. On the way home the rear end is making a loud humming type noice, sounds similar to a really loud electric engine. It gets louder as the speed increases. This one problem
But then on the way the Jeep started ticking. Kind of a loud knocking, which speeds up as the vehicle does. I checked underneath the drive shaft does not move when the vehicle is in neutral and the ticking continues even when the vehicle is in newutral (both drive train and transmission) I am lost and the Jeep is at someones house about 2 hrs away. It drives, but it is noicey and I dont want to blow anything else out or up on it.

Thank you.