Jake:
She's a '77 model. It would be virtually impossible for me to build extra cross members because I don't have the tools to get into such a tight area.
It looks like no foam core, from what I can tell.
Definitely no foam core in there. If it's crunchy, you definitely need to do something. There was a thread on here about how to remove the decks from the 5.2. If you are gentle with a chisel, hammer, and putty knife, you can usually neatly separate the decks so you have full access to the inside.
