Did your old man say the "The Ducky Boys" were the main gang number wise anyway...??
The Ducky Boys terrirory was in an area known as West Farms, a little south of the Fordham Baldies territoty, and were also known as the "West Farm Boys". I dont know about numbers , but they were well known and feared. Other gangs rarely fu**ed with them , especially on their own turf. It was just an area you wouldnt go into unless you were looking for trouble.
In real life there was no big rumble with all the gangs getting together to fight them, that was kinda Hollywood. But the rest of the movie was very accurate . Most of the gangs in the early 60's would generally "patrol" their own neighborhoods. There were dozens of gangs back then, and they fought with fists, chains, bats and knives and would actually make rules on which weapons were allowed at a particular rumble.
Today they just all shoot to kill, times have changed.