Like I said ... my Ford ain't about good looks ... as much as its about utility.
There is SO much space in the cab of a Ford does goes to waste!
anyoldways ... as per all your hints and tips ... I cleaned up the dash ... cut the hole ... braced up the bottom of the dash with fiber glass around the hole ... mounted it back in the truck ... taped and masked every thing off as I wanted ... greased up the tray ... and filled it all in with foam.
The old speaker mount acts as a support for the bottom of the tray.
I let it cure ... pulled the dash back out ... removed the masking , cleaned off the grease ...
Now I'm gonna fill in the cracks with bondo. I'm gonna use bondo ... to make the hole the tray fits in pretty ... then I'll paint the whole thing.
A tip ... there were a couple of spots where the dash covering was cracked and loose ... to anchor that down ... I lifted up the edges ... and filled under them with "Goop" adhesive. I "clamped" it down with duct tape and let it cure.
When I CAREFULLY removed the duct tape ... the Goop held the cracks almost perfectly closed ... nice and solid with NO FLEX. You almost couldn't see the crack.
Then I took a drill with a 1/8" bit ... and drilled a hole at the very end of each crack ... this SHOULD keep the crack from expanding.
Then I took my Dremel with a grinding bit ... and ground a "V" shaped grove following the crack ... do give a good site for the Bondo.
Then I block sanded along the crack ... to make SURE that every thing was FLAT.
Now I'm gonna go ahead and put in the bondo filler.
Check it all out ... put down a second coat where needed ... sand prime ... install.
I'll post the pictures when done.