Beneath the carpet on the "frame rails" on my '93 Bonneville there is factory installed thick, black, sticky, tar-looking "tape" of some sort that seals all those big holes in the unibody. I also see this stuff at the seatbelt attachment points, near the rear window to seal the interior from the trunk area in spots, and to seal where the wiring harnesses pass through the firewall, the interior doglegs, and variouse other areas on the body. I can't understand it, but I can't find this stuff and even reputable body supply houses don't seem to know what I am talking about. What is this stuff called, and where can I get it? About the closest thing I have found is the stuff you seal around windows, on your house, beneath the siding... I want to use the correct stuff, since the wrong stuff may fail and flood my carpet. Please help! Mike