Thanks Jim for the reply. To my belief wouldn't it be necessary that shipping label, shipper and invoice reflects the rev level?
We do not know the reason for change, but there is no change to your eyes.
However when the part reaches the customer, his reason is important to him. It then becomes our duty to identify the part.
Have you made an attempt with customer to understand how he wants the packing slip and invoice to reflect this. Have you informed your customer that you have inventory at various locations of the earlier revision, that he has to consider before you effect the change.
You will have to map this change into your internal traceability / identification process from the date you are informed about after due considerations to your earlier revision parts inventory.