Dealers were notified of the availability of yellow and orange interiors early in '69. The Camaro order form was revised Dec '68 to include orange and yellow; a insert with a photo was included in the February '69 Communications kit and the showroom brochure also revised. While usually mentioned together, it appears orange was not really available initially. The first yellow interior cars were built Feb 18 at Norwood; the earliest known coupe with orange houndstooth is mid-April.
Z11s notwithstanding, neither interior sold well. Winvoices states about 600 coupes with yellow, about 500 with orange. I had two orange/orange Z/28s, one with JL8.