Acid Dipping.

It's worth repeating what Kenneth S said, acid dipping to remove weight (chemical milling, I think) and chemical stripping are two different things.
A buddy had his 38 Chevy dipped a few years ago. It's still in primer, but there is no evidence of rust or the paint lifting yet. I had to cut some panels apart and there is still rust in the seams between panels, but the only way I see of getting rid of that is to seperate every panel on the body and clean the rust out. Not really an option.
I like it well enough that I'm going to have the cab of my pickup project stripped.
Larry T

 

You are correct Larry T on both counts, acid dipping is sometimes called "chemical milling", but like I also said acid dipping causes hydrogen embrittlement, if your "old iron" has cracks already, acid makes it crack even easier, redi-strips claim to fame was "non-destructive" cleaning.