The movie is based on one of Edwin Torres' book series on the criminal life of Carlito Brigante. This is based after the first book in the series "Carlito's Way". Brian De Palma's Carlito's Way (1993) took the first books title because at the time it was decided that they would not take the title of the second book "After Hours" to avoid confusion with the Martin Scorsese -directed movie of the same name (After Hours (1985)).
Since the move is set in the mid- to late-60s, Malcolm X Boulevard would not have existed and would only be known as Lenox Avenue. Lenox Avenue was subtitled Malcolm X Boulevard in 1987.
Carlito Brigante: You know, Nicky, I'd never bother you with something like this, but if we don't find them cats soon, those crazy-ass Italians are gonna come over and start shooting up the black side of Harlem.