It doesn't get much bitchier than changing out the heater core. I had to take off the dash and remove the whole heater assembly. In doing this, I cleaned everything, it was so filthy. The inside of my ducts and doors and everything was black with the stain of antifreeze. Now it's white. I remember thinking I'd never get it back together when it was lying in a pile in my bathroom sink. If anyone wants a write up on this I can do it to save the next person the sheer panic of a pile of dirty nylon parts. I'm just happy that it worked out so well.