I got this with the bunch of stuff that came with my M38A1. I have looked in the manuals and have yet to figure out what it is. I have an idea and want to see what others think it is and where it could possibly go.
License plate holder is my guess too. The metal is very heavy and is heaver than the other formed metal parts of the Jeep except for the frame and bumper. This thing puzzled me for some time. I kept thinking it was some kind of battery hold down too but then the holes would be under the battery. One day I was cleaning parts and picked it up for the 50th time. I just happened to have a license tag nearby and it fits right in the slots. I guess it was an add on like the fog light was.