Are the 12" powerbook parts interchangeable with the 15" powerbooks? I'm asking because the upgrades/repairs that I need/want to do are pretty expensive and if I can just take these parts from a much cheaper machine with those parts still in working condition I would rather do that. The parts specifically are as follows: 1. PRAM battery 2. RAM (I'm pretty sure the RAM is but the PRAM is the important one) Thanks in advance for any assistance!