[DavidG]

Matt,


With the exception of a lock washer, you are not missing anything.

Note the markings from one of the squares with the cross hatching. Look closely at your third photo and you will note that the shoulder of the bolt fits against the smooth side of one of the squares. The other square fits inside the bracket attached to the vertical strainer (in black) with the cross hatching side facing toward the inside of the rumble compartment. Add a lock washer and then the hex nut and that is the totality of the attachment. The disparity in the hole diameters is intentional to provide some slight amount of adjustment of the rumble lid to the body. The cross hatched squares hold everything into the desired position once the nut is tightened.

I cannot imagine a more unpleasant job on the assembly line than making those adjustments hour after hour, day after day given the close quarters of the rumble compartment. It would be right up there with attaching the two bolts at the bottom of the rumble lid that retain the bottom of the rumble seat back cushion.