There is a raised section on the back of the tank, at the front. The pad glues on here, it is 8mm thick hard rubber and bears against the frame down tube to help stop the tank vibrating and cracking the mount.
Pad is same shape as raised section with approx 10mm gap around outer edge. Can't see it on this site but there is a service letter detailing shape and where to fit, if anyone can post a link.