Previous owner of one of my 60s did the entire inside with some heavy tarred metal stuff. Like dynamat. Inside the doors, all the floors, etc. Yes that truck is quieter than my other non-dampened truck, but it isn't significantly quieter. 65mph on the freeway is still pretty noisy because of wind and tires and the engine. I rented a Yukon once and I'd call it quiet. When I drive long distances I wear earmuffs with 30+ db sound reduction. They make a huge difference to my comfort on long drives.
From the For Whatever it's Worth catagory I humbly submit...
@cruiserpilot and others...I drive a 62 with the AT, so my transmission noise situation may be different from you guys in the 60, but I see a lot of guys jumping into the sound deadening/thermal barrier tasks. My final career (post military aviation and movie industry) had a strong acoustics component. I had to really get in the books and get training...and lot of experience to have good understanding. Sound transmission is the factor of acoustics at play in this subject with our vehicles. In the professional acoustics world there are Sound Transmission Coefficient (STC) specifications for rooms in buildings. Movie theaters are a good example. For a theater to get a THX certification, the auditorium has to meet a given STC per frequency so that the movie sound in the next auditorium can't invade.
Sound transmission absorption is frequency specific. By that I mean that a given absorption product will only absorb a limited range of frequencies and that is when it is transmitting via air waves. When it is attached to something solid, many frequencies can travel through the structure and emanate from places you would not expect. A perfect example that we may experience in a home is if you have a powerful subwoofer that is sitting on a concreted slab floor. You can fill all your walls with anything thing and any amount you want, but the sound is gonna travel through the slab and be heard everywhere. This principle explains what @zakthor experiences.
Theaters and such rooms overcome this by not only absorption products but structural isolation ("floating" walls, floors, and ceilings). Structural isolation is not feasible in our vehicles. Absorption products must be dense and thick to have broadband absorption (a wide range of frequencies). That's not feasible either.
Of course few of us have close to OEM vehicles, but in a 62 with OEM exhaust, the biggest noise maker in our vehicle cabin is going to be tire/road noise. It not only can be so loud that it travels in the air around the vehicle, but is definitely transmitting through the vehicle structure. If you run aggressive off-road tread that is not designed with noise-cancelling tread technology (or they have worn poorly), that noise is going to make it into the cabin easily. Can we absorb enough of the noise that is bugging us with just absorption product? Personally, I don't think significantly beyond the OEM absorption liner. Of course, if your OEM liner is a gonner, you need to replace it with something that is appropriately effective.
The only other alternative is to find a happy medium in tire selection. How much mudding do you do verses hardball driving? How much do you need noisy mudders verses AT tires with good noise-cancelling tread design? I've always run AT tires and they used to be noisy, too. Only in recent years has computer modelling permitted effective noise cancelling tread design. I now run modern AT tires that are nicely quiet, look great, and will get me through anything I'm going to encounter in my semi-rural and occasional off-road driving.
By the way, very wise on the ear protection! Long term exposure to those spl numbrers in the 80s is murder on hearing damage.
Thanks for the information. Pretty much as I researched, and in the end found out. I did a lot of research, got into more than a few articles and blogs on the subject. Fascinating subject when I got into it. I had to try, since its really the gear noise, although for some reason I hear the tires more than before. I run Toyo MT's, but I didn't get them for the quiet ride.
Weird part, my BJ74 with no carpet, all steel inside runs at 74 dB consistently. It is by far less noisy, don't understand that.
Anyhow, I'll put up final photos with new carpet and seats soon,