I have a 69 Z/28. I have a code in the exterior trim location on the cowl tag that I can't decode. It is Q223. Thanks

Q=17th day of the month. And your car was the 223rd one down the assembly line that day.
It's described here: http://www.chevy-camaro.com/faq/chevy-camaro-faq-69-location-H.shtm

Thanks. That solves the mystery.