I had a 1960 Volvo P-1800 several years back that was undercoated. I am not sure what they used, it was a pain to clear off of the bolt heads but the bolts looked as good as the day they were put in. There was no rust to be found except for a few rock dings under the fenders. The car was 25 years old by then.
Can't say that I will use it on the truck but I did spray the bottom of the MGA and it is holding up well.
