Help With '97 F150 Undercoating

That's the rub, I don't know and it's why I asked. It's not my truck but usually there's a sticker inside the door and\or some maintenance and inspection literature in the glove box but there was nothing. Whatever it is, it's by far the best I've seen for rust prevention. Except for a spot about the size of a dollar bill on the top of the front cross member the frame so far from what I've seen is rust free. That's saying something for here in salt friendly Michigan. The Prof. that helped me speculated that it may not be something marketed as an undercoating but something the original owner had access to. To him it sounded like some of the coatings used in industrial storage tanks developed to protect the tanks from specific caustic materials they hold or maybe something used at sea. I sprayed the areas I needed cleaned every half hour to hour yesterday afternoon with WD-40 and then PB Blaster and hit it with a wire wheel on a grinder in the evening. It still took a couple of hours but it worked. If the stuff isn't sold as an undercoating it should be. It looks like the bumpy back on a gray toad but it works.