We have all discussed radios, but thought since I was taking some pics for a customer that I would post. The original blaupunkt frankfurt (writing only about frankfurt now) ordered as an option from the factory (a very rare occurrence) or from the dealer had two different designs over the 70-76 run: 70-12/73 and 1/74-76 (do not get me wrong, the dealer installed later on the earlier and vice versa) but BASICALLY these were the cut offs. The difference was the face and surround. Early had a chrome surround with rounded edges and late had a black surround with square edges. The later looked at the time more modern and less reflective for safety standards.
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As you can see two types are displayed along with both the usa and the european faces. The am fm bands are very slightly different but the european will work in the usa. HOWEVER the european face is not correct for any usa car, so if looking for one, if you can get the usa face your 914 would be more correct