i used this guide to remove gpu card from A1225 (EMC2211) 2008 3.06 iMac . found 1 additional screw holding the logic board and positions of some of the connectors were slightly different. rest of it same. Lucky for me I got a used 2008 really cheap and replacing the working GPU card to my iMac which lost its Nvidia GeForce 8800 GS (661-4664). I hope it works. Thanks to the original author for the instructions.

Perfect guide. Images are very clear. Just completed replacing worn out battery with a new one purchased from ifixit and everything went smooth. Phone is in perfect working condition. Thank you.