did was called ZEBART

then the epa shut them down man
I've seen many cars that had the ZIEBART treatment and still rotted away,it just took a few years longer..my dad had a '76 Torino wagon for a company car at the gas plant,the dealer insisted it should have the rustproofing..--it had rot showing by 1979 in the rear "dogleg" area and wheel wells in the rear...maybe they didn't spray enough in those areas,the rest of the car held up good..
I recall the stuff they used being a yellowish goop that would only semi-harden up..but I have seen quite a few cars that had it that didn't rust out too..(back then I believe they gauranteed "no rust or your money back" or they would repair it no charge..maybe that is what put them under ?)
Best factory undercoating I had on a car was my '85 VW Jetta diesel..that car had stickers from a lot of different colleges all over the USA and had 252,000 on it,yet the underside was still pristine..looked like some kind of sprayed on melted plastic stuff...maybe the car didn't spend much time in the rust belt..but I have peeked under a lot of other VW's like it,and only a few had any real rust to speak of..
I used to sell some stuff years ago made by either Morton or Car-Groom that was really good undercoating,there was 3 different types ,all were specially designed for certain areas..inside doors was one,another was for in the "blind cavities" like rockers,and the other was a "general purpose" one for the undercarriage..the one for the doors would flow like paint,then gel up--the one for rockers went on thick and wouldn't sag or run,the undercarriage stuff would harden up on the surface but remain somewhat flexible underneath,so it wouldn't crack or flake off..
I would never use Dupli-Color bedliner,after having a few sour experiences with it and reading online about dozens more...Herculiner is good though..
I see Rustoleum has one out now too,but I've never tried any yet..