What sound/heat deadener do you like?

My truck (82 D150) came to me with bare floors. It's hot and noisy, so I'd like to add some kind of sound deadener and insulating material to the floor, firewall, and rear cab wall. I will probably do inside the doors when I get time. I have vinyl flooring to add after laying down the sound and heat deadener. What kind of material have you used, and how well did it help after installation?