How does this heater box retainer rod (J-hook) work?

Okay, so the rod is clearly not threaded. The bottom of the box also does not appear to have any thread mechanism. There was also no bracket inside the box. Here are a couple of pictures of the inside and outside of the box with the J-hook. I had to repair the box with some JB Weld. There were two guides (almost like small walls) inside the box on each side of the hole.



Here is the hole on the outside of the box where I also had to repair it. I then fed the hook through and it just so happens that the longer, flatter hook end conforms to the bend towards the firewall side of the box.






Here is a picture of the rod coming up through the box. The more curled end of the hook just barely sticks up above the top lip of the box with the foam seal on the box.



So is it safe to assume that there should be a spot where that curled end of the hook attaches up under the cowl?