1968 GTOs used the same decal/sticker as the 70-72 GTOs did and they are inexpensive and available right here from Performance Years. They were made in white, black and red depending on the cars color combo.
If interested, you can go to my site. I have an 'ID guide' section showing all years and models of Pontiacs. There is a pic of a 68 GTO with the decal in the correct position.
Steve
Hosting-
12th annual Pontiac Heaven April 8-11 Phoenix
Make plans to attend now.
www.pontiacheaven.org