Sandblasting. There isn't anything better, but its a big mess and requires a hefty air compressor and a pressure blaster. I won't do it any other way. It cleans off everything and gets into places you just can't with chemicals. Its nasty though.

http://devestechnet.com/Home/SandBlasting


Deve

1950 Chevy 3100 Deluxe Cab
1950 Chevy 3100 Standard Cab
In the Stovebolt Gallery
The Think Tank
More info and tips at Deve's Technet