If you send an email to: ArchivioStorico@alfaromeo.com with a request for information regarding your Alfa they will get back to you with an email telling you what is in their records. I did this for my Sprint Speciale and this was their reply.
Dear Mister Hamilton,
with reference to your request we are informing you as follows.
According to our documentation files, the chassis number AR 101.20.00413 originally corresponds to an Alfa Romeo Giulietta Sprint Speciale, manufactured on the 9th March 1961 and sold on the 13th March 1961 to Società per il Commercio dei Prodotti Alfa Romeo. Lugano, Switzerland.
The body colour is Alfa red.