Exactly as this post title states. I am completing my collection of past gen systems, and I'm only missing a PS3. I intend to mod it to upgrade the hard drive and play backups. I realize I need to find one that is 3.55 and below, right? What is the best system to shoot for? (Phat, slim, etc) Is there serial numbers or certain boards to look for? If I can't find one that is 3.55 or below, is a mod-chip possible? (I've read a little about it, and I'm comfortable soldering, but what chip is the best, cheapest or easiest, and what systems do they work with?) Basically any advice is helpful, and thank you ahead of time.