Disclaimer: Links on this page pointing
to Amazon, eBay and other sites may include affiliate code. If you click them and
make a purchase, we may earn a small commission.
That is a good comprehensive start but RPO codes do get reused, so it's important to use a contemporaneous (aka "back in the day") list like the generic info packets in the GM Heritage Center archives when possible.
Otherwise every so often you are going to see something that just doesn't make sense.