Car Audio in Early-A bodies?

Question for you all...will any B-body radio fit in an A-body? I am looking to repalce the cassette radio that came in mine with an original unit..I have XM isntalled and so coudl care less if the radio actually works or not. I found a B-body radio from a coronet that looks right but want to be sure before I spend the money on something I have no use for. I have a 65 barracuda. Any suggestions or help please respond or PM me please.