Doug,
3-m Body panel adhesive.
It's used on all the later model automobiles to fasten all the sheet
metal panels and inner supports.
Tough stuff, and it'll ever shake loose, crack, or separate from the
repaired area.
It also dispaces moisture so at that particular repair area it will be
good for a long time.
Available at any body shop supply.
An excellent , long term repair compound.

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Subject: How to fix / External body panel internal supports coming loose

Anybody know how to re-attach the interior cross over supports in the
back of the van to the outer body skin.
I have my door panels out and noticed the cross over supports are not
stuck in the adhesive the factory attached them with.
You can wiggle them and they are totally free.
Does 3M or other make a goop to re-attach?
Thanks
Doug