Sound proofing the cab question

[truck69]

My 69 chevy has a way to go before I start thinking about installing a new radio and such but wondered something. As I drive it now I can't hear my self think as I can hear the road around me and the engine as I drive. When I get to the point where I take out the seats and carpet and put in the sound proofing, how big of difference does that stuff make? Back then I dont think they were thinking about winning a stereo sound off. Any help would be great.

Thanks. Truck69.