Begin the system diagnosis by reviewing Driveline Disassembled Views , Propeller Shaft Description and Operation , Transfer Case Description and Operation for the transfer case NVG900 and Rear Drive Axle Description and Operation . Reviewing the description and operation information will help you to determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the description and operation information will also help you to determine if the condition described by the customer is normal operation. Refer to Symptoms - Propeller Shaft to diagnose the system and locate the procedure.