My recommendation would be to leave it there for the sake of originality, and hide a more modern radio somewhere else. In the glove box, or just get one with a remote.

Or perhaps you could spend large and have one of the specialty car radio places replace the guts of your old radio with modern technology... check for listings in Hemmings.

Or keep an eye out for another radio like the one you have that works...

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-Matt I ♥ my ♂