The undercoating on the FJC is not like any undercoating I've seen before. I almost wouldn't even call it "undercoating". To look at it, and feel it, it seems like it is a soft rubber/foam coating. In places, it is up to an inch thick. It's more of a sound deadener and not a rust proofing thing. Probably does both, but it's not that thin black crap that gets sprayed on.
I agree it is VERY different, however before we all go run out and use it, I would love to see how well it actually holds up! Will it work to stop rust? Has it been used on other trucks besides the FJ?
Zack