I did a quick look through every 747 layout listed at https://www.seatguru.com/charts/longhaul_economy.php https://www.seatguru.com/charts/longhaul_economy.php

I did a quick look through every 747 layout listed at https://www.seatguru.com/charts/longhaul_economy.php https://www.seatguru.com/charts/longhaul_economy.php I don't see any 3-5-3s - everyone was a 3-4-3. If anyone was doing it, they've since retired the plane/layout.