Well all of the above. I soaked it in evaporust for 3 or 4 days and flushed it out. Then it was re-cored and assembled using the original tanks. I think the brazed area's were ok, so he just soft soldered the heck out of it and tested it. I have seen a lot about this subject, and it seems a lot of people don't wanna use their original. They just buy aftermarket, which of course is just fine. I dropped it off on a Friday, and picked it up Tuesday Morning. I will pull my original in the coming weeks and clean it, check the date and find out what it will entail to get it up and going. Maybe mine can be saved, and repaired without a re-core. I will also record the second hidden VIN at the same time... D