Soundproofing a Diesel

[79vette]

Has anyone used this product from LMC?
Https://www.lmctruck.com/1973-91-che...nsulation-kits

I have a lot of engine noise in my M1009, and cannot drive on the highway without hearing protection. I don't need a Lexus, but I would like to at least be able to talk to a passenger without screaming...

So far I have used Dynamat/Peel n Seal (didn't have enough dynamat to finish the bed and they seem like the same thing to me) and 0.315" closed cell foam to cover the floors and firewall. I have not put down mass loaded vinyl yet, but my floormats are .375" heavy industrial rubber and at least 1lb/sqft and I imagine they would work similarly. The foam really seems to help with heat, but the truck is still unusably loud.

I haven't soundproofed the doors yet, and I need new vent window weatherstrips. But other than that I have no idea what else to do to make this quieter. This truck has way more soundproofing than my gas K5 and my C30, and it's still unbearably loud. Did everyone just wear earplugs when the 6.2 was in production, or is there something I am missing? Is there any kind of sound insulation I can put on the engine side of the firewall or on the bottom side of the transmission tunnel?

I built this to be a camping rig to access remote canyons and mountains, but none of my climbing partners will ride in it because it's so miserably loud. I daily drive an 88 one ton square body and a 79 Corvette with side pipes, and even with hundreds of $ in insulation and days of work the M1009 is still WAY louder than either of my other vehicles, which just have the stock 40+ year old interiors...