Just talked to Mr. Ron Ross at ATL and he was cool enough to send me the correct aluminum fill plate for the MAX option. He said he's never seen that happen before haha! Below is the `Cuda's red aluminum plate which weighs 2 pounds less than the blue steel plate.

As for the 6 black plastic tabs, they are there to help grab onto the aluminum box so it does not move around. The fill plate is mostly bolted down onto the hard rubber bladder inside. If it were not for the 6 black tabs, one could just push down on the fill plate and the hard bladder would shift inside the aluminum box.