Any spray-painted striping that was applied after front sheet metal installation had to be performed in the in-line repair booth. Z10s, Z11s and Z/28s were processed that way and had to be released to final assembly so as not to over-schedule the booth. Almost 25% of '69 Camaro production received the D90 striping, adding significant burden to the area. Much faster and cheaper to apply a decal.
BTW, the DX1 stripe was finished in the same fashion-hood portion was the same decal used for D90.
http://www.camaros.org/assemblyprocess.shtml