Since the sound seems to be drawing your attention to the last cylinder in the bank right at the Firewall, the next place to look would be between the Transmission and the Back of the Engine Block inside of the Bell Housing ...for a Possible Cracked Flex-Plate. Look for signs of having Bad Motor Mounts with evidence of their "Bulbs" being collapsed and a "Black, Sticky Goo" getting ejected on the adjacent areas of the under Wheel Wells.
Just know that this is one possible cause for eventually having a Cracked Flex-Plate. Pull out the S/S Round Inspection Port under the Bell Housing AFTER safely Jacking and Supporting the SUV on Jack Stands and Chocking the Rear Wheels, front and back. Then hold your Cell Phone under that area and record-listen for the rhythmic sounds of any knocking concentrated inside of that area: