I just went through Phase I of my cleaning. It is a tremendous amount of work. I'm shocked the car even ran. The amount of rust was staggering.
I found a method of filling 1/2 the tank with water, add a gallon of muratic acid and then the rest with water. It did a great job, but I need to do it again. It still has a bunch of rust left. I flushed and flushed and flushed, shook and shook and shook. I was sore the next day. I used golf balls to brake up the rust. I would not do it again. I finally had to use a vacuum to get them out. (I know, I know no vaccums).
I bought a 9.99 hair dryer from walgreens and tapped it to the tank. I ran the sucker for at least an hour and it didn't blow up! (Hair dryer, not the tank.) I've got the tank in the house now in the cool a/c. Wife is not all that happy about it.