10mm hexagon drive (Allen key type) with 3/8 socket, not sure if you can get a 1/2 socket passed the cam, (bit of a tight squeeze in some places) you will properly need to rotate the cam to gain access to some of the bolts. Make sure the hexagon drive is well seated to the bottom of the head bolt and keep it vertical otherwise you could damage the head of the bolt. I used 10mm hexagon dive with 3/8 socket then converted it to 1/2 drive just outside the head so I could use my 1/2 torque wrench when tightening back up. Do you know the correct sequence of undoing the bolts?
http://www.cygnusx1.net/Supra/Librar...ion=EM&Page=39