Walked my wrecking yard this morning. All of the 1968 Cougars have the sticker on one or the other shock tower, driver or passenger. No difference between San Jose and Dearborn, same pattern on 1967 (all Dearborn).
Going to make a retraction. Only checked 1968 cars, only made notations if they had original stickers, no difference if big block or small block, no difference with or without A/C. I have 18, 1968 Cougars. All of the San Jose cars have the sticker on the driver side shock tower. All of the Dearborn cars have the sticker on the passenger side shock tower. I took numerous pictures showing the positioning of those decals, they are mostly straight, some higher than others. Some closer to the apron, some wrap partially around the curved section.
Again, my bad for not being more careful.