Just Lou offers key forensic evidence...If I had to guess, I'd say it's an Electro-Voice Model 654. (see his photo, stipulated as Exhibit 1 in an earlier post)
Look for the photo of an EV Model 674. I think that's a better match. Never saw one in real life, but I bookmarked a web site with vintage microphones a long time ago and I was pretty sure it was a 674.
I hadn't given it much thought for a while, but a musician buddy tipped me on a couple of vintage microphones he saw at an antique/re-sale shop in the neighborhood...with the specific description that one of the mic's looked like the ones they used in the hearings. He's not a Godfather fan, but as a working musician he has an appreciation for vintage equipment and seemed pretty confident it was the same one.
The committee members are all using a different microphone -- they appear to be Electro-Voice Model 665. In both cases, it's equipment that would have been manufactured in the early to mid-1950's so these are historically accurate props. What's not right? The cable and connectors in that scene...the original equipment in that era would have had a connector held in place by a concentric ring and NOT the modern push-and-click XLR connector shown in the photograph.
Anyway...I'll find my way to this place and if it's the right thing at the right price, I'll post-up again.
tony b.