They were a dealer installed option in the A & B bodies....factory option in the C-body according to the owners manuals. In a '66 model the fender tag code would be R3 for the standard AM-FM and the build sheet code is 423. The earliest AM-FM I've seen was in a '63 Imperial. It was a Delco unit with a Chrysler part number tag on it. I've seen the same type unit in the '64 Imperials and New Yorkers.
