RPO stands for Regular Production Option and is General Motors’ standard coding for vehicle configuration options. 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.
During earlier GM production years some of these codes were added to the Cowl Tag as a replacement of the previous Accessory (or ACC) Codes which were a single alpha character that was stamped on the Cowl Tag. What those letters meant depended on where the tag was stamped and was prefixed with a single number (except position 1) and those codes varied by year, make, model, and assembly plant. The earliest years that RPO codes were used was in the early 1960's at the Fremont, Ca assembly plant. In an attempt to standardize across all assembly plants, the use of ACC Codes was dropped for all of the GM line except for Cadillac which maintained the same code structure until the 1970's.
NOTE: The RPO Decoder can be used for Cadillac even though they didn't use RPO codes. If you select Cadillac you can decode the single character codes using the same tool
Later on, the RPO codes identify the base model of the vehicle along with options such as paint color, engine, infotainment system, wheels, etc. In some cases, the RPO has become so identifiable to a specific vehicle that the code has become a part of the vehicle’s model name: Camaro Z28, Silverado Z71, Corvette Z06, Corvette ZR1.
What we have attempted to do is to give you the ability to research RPO codes from 1964 - 1972 by using the Year and Make of the car to find and decypher the RPO code. While most RPO codes were shared by all of the GM line (except Cadillac) there were exceptions. The most noticeable one are the "L-Code's" which denoted the engine type and HP rating as well as some Division specific codes, for example, "Z-Codes'" that were used by Chevrolet. We are working on translating these to make them Division specific. It will take some time but you can check out the latest code updates by clicking here.
The RPO Decoder is a natural extension of the Data Tag Decoder and you can try it out here. It is still in beta and we do limit the number of code searches to 8 and we are working on correcting codes as quickly as possible.
ALSO: Have a Factory Build Sheet? The RPO Decoder can also be used to decode all of the RPO codes listed on the bottom half. The Cowl Tag has a limited amount of space but the Build Sheet has most if not all of the RPO's that the car was assembled with.