I just purchased a brand new cab for my deuce and a half (basically a Jeep tub). Mine is not in any sort of bad shape, but it would take me a couple of days to repair the little bit of rust in the rocker panels, and I got this NOS cab cheap enough that I couldn't say no. The cab was galvanized, and then painted very poorly (no primer), so I've had it sandblasted and before I prime, paint & install it - I wanted to think a little bit about insulation in case there's anything I want to apply to the underside of the floorpan. I think I might end up using some type of dynamat-type product on the firewall and the back of the cab, but is there anything I can apply to the underside of the floorpan to build-up some serious insulation? Is there any type of water/weather-proof spray-foam that I could use, or ____? Just wondering what's out there. I've used Line-X on a Jeep tub in the past, and that was a DISASTER. Don't want to repeat that.