Ok, got a question. Bought a '04 Silverado extended cab in June. I noticed that when I got it, the undercarriage (frame, leaf springs, inside of body panels) was black. Cool, but I was told it wasn't rust proofing at the time.

Recently I was under the truck and noticed that wherever this back was, it was soft... like an almost gummy substance. it was obviously sprayed on, it stopped on the axels just before the brakes, wasn't in the engine compartment or on the gas tank. Obviously someone had painted the underside. Is this a form of rustproofing, or maybe just some other way to make the undercarriage look better?

rubberized undercoating to keep the actual metal surface from seeing the elements and rusting while making everything nice and black.

That was my thought, but the dealer said it wasn't rustproofing (though he was trying to sell me an 'environmental' package that included rustproofing).

thje frame has a black "****" on it from the factory...but it may have been undercoated as well...that was big about 25 years ago...dealers "undercoated" your brand new car for another 300 bucks...which involved some make-ready clown spraying that crap all over EVERYTHING.....what a nightmare to work on

Yeah, that's pretty much what it is. Though the dealer said it wasn't their doing so it could have been from the original dealer. The 'coating' is well done, if nothing else. It isn't where it shouldn't be, (wires, muffler, wheels). Dunno if it was an aftermarket or not.

I guess its fine if done right...but when some clown has rust-proofed the brakes,wheels,and wire harnesses,it kinda gives ya a bad outlook on the goop

I know Subaru does this but they use a waxy/greasy substance. It looks terrible and if you got under the car and didn't look at the whole underbody, just the oil pan or tranny pan, you'd crap yourself and start thinking you had a major leak going on! LOL!:D What's worse is when it does have an oil or other substance leak it loosens this crap up and becomes slime on the bottom of the car.... ick!