I know this is old, but I came across this exact situation on my modified car.
If you convert to a 9" in these cars you need to put a flat plate over the hole in the body mount that the 8" snubber plate version had.
What happened here (and what I did) is to lop off the rubber snubber and bolt the plate back on, therefore covering the hole.
In my case I left a little rubber on the leading edge and flipped the plate front-to-rear for a little bit of extra length.
You might be able to see that if you flip the plate around it looks exactly the OPs plate.
In other words, both cars are modified and not correct for concours.