I have found them glued to the bottom of the glove box inner liner and also on the backside of the rear panels in the back of the car for storage. The sticker so to speak is about is a white paper sticker with several lines i=of three digit number/letter codes spaced apart from one another. At or near teh bottom line is the paint code. IT will NOT say paint code...but rather give you a series of numbers and letters (such as 516H) and may have BC/CC behind it. It may have a (WA-) prefix in front of it...so it would possibly look like (WA-516H BC/CC) A "U" May also be before it to identify that it is the TOP or UPPER color. Due to some cars havwo-tone paint jobs and the "L" is for the lower color...and the "L" may be the same number due to both upper and lower colors are the same due to not being a two-tone car.
You can call into a GM dealership and give the parts department your VIN # and they should have that info on file.
"DUB"