from what has been reported previously, all 'factory original' ZL-2 hoods had a 'date code' stamped on the rear drivers corner of the hood, on the side at the back. See attached photo of my original hood with '25' stamped. Note that the stamp in my case is 'upside down'. I'm totally unsure if they are all like that or not, since I only have the one. The 25 represents the week of the year, so 25 would be sometime during July of 1969 (since '69 is the only year factory cowl hoods were used). My car is an 09C production with a 27August engine and most parts being produced in August 1969.
Supposedly, repro hoods and even post-69 model year 'OTC' hoods were not so stamped?