Did you check this link?
http://autocolorlibrary.com/cgi-bin/...truck-pg01.jpg
I got a 1972 truck color of Dark Blue--coded 523 2366
The 523 is the paint code you need for ordering PPG paint
My 1970 Blazer is Dark Blue also 4508AA is the glove box option sheet code, and it ended up being PPG code 508 for the original paint color code I needed to get the paint. They will be able to help you at any automotive paint store. Here is pic of my glovebox option sheet.