I used “Fat Mat” on the inside of the firewall and on the floor , ceiling , inside the doors , and back wall of the cab
Then installed a replacement firewall pad from a vendor
Order about double the fatmat you think you will need
If you don’t you will not have enough
Then we used some reflective foil insulation
Followed by a foam mat and carpet
I don’t know if anyone is making new ones but the diesel pickups had an extra insulation pad on the firewall under the hood to block the noise and heat