If you're trying to determine if your car originally came with the AM/FM radio, there's little chance if you're missing all the parts. HOWEVER... if you still have the blower motor capacitor and wiring on the firewall (see the AIM, UPC U63/U69, Sheet A5), that might help since it only came on U69 (AM/FM) cars. Of course, it's not "proof positive" since it could have been added at any time. (or if it's not there, it could have been REMOVED at any time!!)
Ed