The early "smiley face" logos were pre-'66, and all of those were top control with paisley tolex, the common "Sunn O))" logos continued through the 70's, but they added the "®" in '69; the same time they switched to the rectangular pattern grill cloth.
All of the above could be changed however, and the surest way is to find the inspection date on the chassis, usually written in grease pencil on the chassis or on a white and green inspection sticker.
Or... post some pics here and I'm sure someone can narrow it down for you pronto.