I was planning on using Line-x, or something like it for under my fenders, cab, and on the cab floor and inner firewall. I thought I would use some stick on insulation like Dynamat for the entire inside of the cab. Then the bed liner over it on the floor and firewall. Still thinking on it, but with the thin insulation, and some thick bed liner completely covering it, and sticking to the steel cab floor around the edges it should stay dry underneath, and be really really quiet. And if for some reason I want to remove it, it should be easier than if it were stuck right on the floor. I am also using a 4-53T Detroit engine, so anything I can do to reduce noise will be well worth it.
