Hack 85,
Find a local "Chemical Strip" place near you and have them clean it for you. There chemicals won't hurt the tank and will clean it right down to the tin coating. I had mine done for about $135.
I've heard others say they've had there local radiator shop "hot tank" a gas tank to clean them. I've never done one this way, so I can't tell you how well it works.
Mike B
