I used a propane torch and scraper on my 68 fastback. not fun but easier then I thought it would be .
I do have a 4 post lift that made it easier .
I will have the underbody sandblasted before paint.
Thanks a bunch, the propane torch and a scraper works great and is pretty fast also. The little it leaves behind will be easily sand blasted away. I removed more undercoating in an hour this evening than I had in weeks.