Ramcharger vibrates after using 4wd

First are you sure it is actually coming back into 2WD?
The only way to check 4x4 drivetrain is to LOOK and FEEL. You can not check drive shafts "in the vehicle. You must unhook at least one end, and move / articulate the U joint through it's range to feel for dry, crushed, ruined bearings, etc. Don't forget the knuckle U joints as well. And look for junk in the wheels, mud, snow, etc, dirt..................."out of balance"

Usually you can tell by the frequency whether it's a (slower) wheel/ tire/ etc or a driveline, much faster.