You could also verify the fluid level at the OEM plug on the front of the differential cover. With your truck level check the height of the stock fill port to the ground (or smooth surface like a garage floor), then do the same with the B&M fill port. Maybe there is a discrepancy. I would fill using the OEM hole and verify the 2 holes are the same height. You would only need to do this once and note any difference for the next time you drain and fill using the B&M ports. You don't want to overfill.