Where did you find the RPO codes on an '82? They don't have a SPID sticker on the decklid. The build sheets I have seen don't use RPO codes. The window sticker has them, but it has the description as well.
usually you can find a build sheet for the car tucked inside a door panel or under the back seat somewhere.
I've seen build sheets before. Alot of codes on them. The window stickers give you a list of options and some standard stuff as well. But do not tell everything.
If you are feeling froggy enough to do it.
Get the proper tools for removing door panels and take a look.