But it won't be tight for long. It looks like, when you tighten down on those slanted pieces it pulls the clamp around the terminal closed...the pieces slide sideways as you tighten since they are slanted. If you look on the left side of that little plate around the battery terminal, you will see the other part of the clamp coming up from under the plate and up the side a little. You can't see the clamp really good since it runs under that terminal plate, but it's there. Without those slanted pieces on the right side, you no longer have any clamping force left.
I've uploaded two pics for you...in one the pen is pointing at the left side of the clamp and the right side on the other. The clamp runs under the terminal plate.
If you don't keep that clamp tight, it will eventually come loose from vibration. If you can't find that little piece, just call your Ford dealership...they'll probably sell you the whole clamp, but it can't cost that much. Good luck!
06 Stang GT, Yeah I got stuff! Check out my profile for the low down.