From what is looks like someone will have to invest $5000-$5600 to get the unit running smooth again. The 2004 Peak only has 2 heat exchangers. I have a few of them. Great units. My 2004 looks damn near brand new with 5600 hrs on it.
Just adding my two cents, I am familiar with this particular unit and can recommend it for anyone who has the technical know-how and the time to invest in it. Many parts of the unit are in excellent shape (others... not so much, heh), and while it's not going to be a brand-new TM by any stretch of the imagination, it would be worth its price in parts if you have another unit that needs patching up.
For those who are tech-savvy and don't mind a little grease on their sleeves, this would be an excellent buy.
The fellow selling is one of my guys and is ethical, friendly, and very motivated. Don't buy it expecting it to run right off the block, but with the right amount of effort there is still life left in it.