Z28 Spolier Markings

[Iowa Jon]

Hi,  in the process of stripping the paint off my rear Spoiler I found some markings.  When I lightly sanded off the paint from a 1977 repaint I noticed the markings.  It appears to be a Squiggly line and underneath is maybe " D,O,5 or S, ?, ? then 9N " you can make out the 9N in the pictures. 

I tried to look through the forum for some other examples of these markings and how they were used on the assembly line but i did not see any Spoiler examples.  Just curious

Jon