I’m looking to insulate (thermal and acoustic) the cab of my ‘95 Dakota Ext cab.
there’s some pretty big open cavities under rear side window behind and below the speakers.
I’ve already lined the underside of the roof with silverback and filled all of the unreachable areas with expansion foam. Any suggestions for those big cavities and inside doors?

 

The spray-foam insulation works pretty good, and sticks to darn near anything..... Trouble is, it's porous, and will hold moisture in there as well..... The stuff you used on the roof would likely be better...... Or even bedliner, the spray on stuff. Insulate, and rust-proof at the same time.

 

I used some self adhesive sound deadener pieces on a GMC truck I built a while back. I can't remember the brand off hand but they dropped the heat from the roof immensely. They also stopped the booming of road noise. I got them off Fleabay. They are 12 inch square, self adhesive panels. A bit pricey but southern Indiana summers are NOT something to take lightly.