Well i'm selling my iPhone 3GS so I can get the 4. But the person I'm selling it to would prefer it was unlocked so they could keep their current firmware. At the moment its on 4.0 with the modern firmware 5.13.04. Luckily its SSH's are backed up on Cydia from when it was on 3.1.3. If i downgrade can I then jailbreak and unlock it??