Just do what you did before, place a magnet near it. This time,
let it stick to the hard disk.
As for the RAM that T43 is using... it's being discontinued by IBM,
so I can't tell what it's using. You need to get a third-party
software to find out what type of RAM it's using. That software is
CPU-Z.
Download it, unzip, select the Memory tab. Everything is written
there.