WOW! Now that's a rare piece! Yes, that's what you will need. Growing up my family had a 1977 Sedan deVille with the factory CB and I remember the good 'ol distinctive tri-band antenna with its distinctive center "bulb" on the mast for the CB. Starting in 1979 the Cadillac radios were electronically tuned and also had optional CB radios through 1985. Have you thought about one of those more modern am/fm CB radios or are you going with the 1978 radio to be old school? Have fun with the project and post some shots of how it all turns out! Dave
