I have an '89 LWB that has been almost entirely replaced over the last 3 years (engine, radiator, manifolds, cat, exhaust, coils, shocks, alt, battery, rotors, drums, rims, etc.) and is in pretty cherry condition EXCEPT the underbody is getting pretty rusty. I undercoated the entire thing last fall (nearly knocked myself out with the chemicals) but it's coming back. I now use the rig as my summer beach rig (lots of salt) and winter daily driver (my wife gets the Discovery and we garage her car). I'm trying to restore the underbody as best I can so that I can keep the truck at least 5 more years. Here is a link to some good info that might help anyone else doing this.
http://www.geocities.com/goodytommy/rust/

Aside from dismantling the entire frame, can sandblasting the underbody help? I've never done it and would probably bring it to an autobody shop to have it done. WHat do you guys think?
Jim
PS I searched all the archives and found POR-15 references but not enough about sand blasting

Two questions (for all):

1. What about using ATF to remove rust?

2. Why not POR-15?

Thanks