It is a 74 cuda.
the holes in it are the drill out holes from the original spot welds. After viewing a lot of resto pics, I find nothing is to be in the spot. The original rear panel had a more of a "journal" to weld to. My new panel does not have as much of a journal to weld to.
I welded it to the rear panel with what I could attach to and seems to have accepted the positioning well.
Pics to follow.