Each RPO code is a combination of three alphanumeric characters (like Z71) that refers to a specific option or modification to the vehicle as built during production. The RPO codes identify the base model of the vehicle along with options such as paint color, engine, infotainment system, wheels, etc.
Please see below a list of ACDelco RPO CODES in PDF format
Some of this post was pillaged and plundered from
https://www.newgmparts.com/decoding-general-motors-rpo-codes
