If you have found your RPO codes label, usually posted inside the glove box,
but can't interpret what they mean, go to:
This link gives you a chart of boxes to put in the codes listed on your label.
When you then process this, it will give you a list of what the code numbers
You may need to run several pages, depending on how many options you
have on your vehicle.
However some codes may say, not found. These are internal codes used
only for the build process, and do not reflect options on the vehicle.
Hope this helps. It did for me, when I acquired my truck used, with no info.