You are right. They were from the Bronx, not Brooklyn. I think Dion is the last of the four left. Great close harmony.
Dion split from the belmonts in the 60s. Did semi folk songs in the late 60s. Then did Christian music for a while. He never hit the heights like with the belmonts.
Interesting movie on the era in the Bronx is The Wonderers. A better movie of the era from Brooklyn is The Lords Of Flatbush.