There often seems to be some "build debris" metal in the bottom of the tanks.
That is very telling about Morgans attention to detail.
John, if you are using the top mount for that battery a tip to save you grief is to cut off the top of the protector caps that cover the unused new battery post exposing the top connection point. By using it that way it will trap that pesky little nut and keep it from disappearing under the battery.
2019 M3W Sold and is now in Las Vegas enjoying the showgirls :-)