Black-out Paint Applications
Certain first-generation Camaro models had semi-gloss black-out paint applied to the body to influence the appearance. There were two types: a "ground-effect" black-out applied to the rocker-panel/body-sill area for certain exterior trim options and a blacked-out tailpan applied to SS-396 cars.
Body sill black-out paint was applied to Z22 (RS) cars in 1967 and 1968 and to Z21 (style trim) and Z22 (RS) in 1969. But there were several body colors that were simply just too dark for this paint scheme to be effective and for these colors, the body sill black-out paint was omitted. Additionally, the body sill black-out was omitted for the 1969 Z11 Indy Pace Car convertible trim package and the 1969 Z10 coupe trim package. A Chevrolet Product Bulletin dated 2-4-69 describes the Z11 (Pace Car trim package) package and includes this instruction: "Body sill to be painted white instead of black." Although no instructions have been found for the Z10 coupe, the intent would have been the same.
There was also a paint color exception for the SS-396 tailpan black-out, but it was limited to black vehicles and the Z11 and Z10. Black SS-396 cars would not have received the (semi-gloss) blacked-out tailpans. But it should be noted that a few original paint black SS-396's have been observed with blacked-out tailpanels - the paint difference is only visible at the paint tape line.
http://www.camaros.org/exterior.shtml#BlackoutPaint