I cannot imagine a brand new engine design would revert back to spark plug wires and remote-mounted coil packs. For a number of years now, spark plug coils snap over the spark plugs, eliminating high energy spark plug wires. Maybe your terminology is incorrect.
I understand tweaks were made to the 2021 E350 and E450 cut-away chassis to increase GVWR, but I don't how it was achieved. I did read that the "made for motor home" version has beefier front and rear stabilizer bars. Maybe that change alone increased GVWR. It would be interesting to read the specifics on how GVWR was increased.