Comparing the AMD panel to some originals I found four obvious differences with the strengthening ribs. A little time with a propane torch, hammer and dolly and a body file fixed it.
Also had kid's cub scout Pinewood derby and we had a separate adult race so we needed to build two cars. Kid's was a zombie apocalypse car and mine was of course a road runner.
Some more progress, trunk floor is 90% welded and ground so started fitting extensions and quarters. They will need some tweaking in a few areas but not too bad overall.