I have a 1987 Jimmy…350, 700R4, 4X4. I am trying to find a vibration. Symptom - After reaching cruise speed and trans shifts into OD, RPM’s are low the vibration is pretty bad. Smoothes out when I accelerate. The rear end sometimes pops when taking off and already moving. When I stop the rear end drops after a few seconds, it also makes loud noise when hitting speed bumps etc (clunk clunk). I have found nothing obvious yet but need to dig in a lot deeper when I get time. Anyone had a similar situation?