Hi Dave,
As far as i'm aware,Beta's left the factory without radios.
In the UK, we always received cars at the dealer without, and where i worked we mostly fitted Blaupunkt
unless the customer requested otherwise.
It's possible that your US importer fitted sets before being sent to the dealers.
In related to: Lancia published a guide as to aerial fitment which I only saw recently somewhere on Facebook.
and: at least the later Betas were wired to accommodate an electric aerial.
Hope this helps slightly!
Nige
